Node architecture for modularized and reconfigurable optical networks, and methods and apparatus therefor

ABSTRACT

An optical transport switching system having an all-optical switch that can be selectively configured to provide cross-connection and add/drop multiplexing functions. Optical circuit cards are provided in a chassis/bay, and connected by an optical backplane. The circuit cards may include access line interface cards, optical access ingress cards, transport ingress cards, transport egress cards, and optical access egress cards. An optical switching fabric provides selective optical coupling between the cards. The all-optical switch can be used in an optical network that allows external/access networks to access the optical network, including access networks that use Gigabit Ethernet or SONET signaling. Wavelength conversion is provided for non-compliant wavelengths of the access networks. A local area network enables control and monitoring of the cards by a local node manager.

FIELD OF THE INVENTION

The present invention relates to an optical communications network and,more particularly, to an all-optical switching system for use at nodesin such a network, and to a control architecture for such a network.

BACKGROUND OF THE INVENTION

Fiber optic and laser technology have enabled the communication of dataat ever-higher rates. The use of optical signals has been particularlysuitable for use over long haul links. Moreover, recently there has beena push to integrate optical signals into metro core and other networks.Conventional approaches use switches (i.e., network nodes) that receivean optical signal, convert it to the electrical domain for switching,then convert the switched electrical signal back to the optical domainfor communication to the next switch. Moreover, while some all-opticalswitches have been developed that avoid the need for O-E-O conversion,they possess many limitations, such as their being time consuming anddifficult to configure or re-configure.

Additionally, conventional network infrastructures have otherdisadvantages, such as inflexibility, inefficient bandwidth utilization,fixed bandwidth connections, and hardware that provide overlappingfunctions.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an all-optical switch thatcan be selectively configured to provide cross-connection and add/dropmultiplexing functions.

It is an object of the invention to provide an all-optical switch foruse in an optical network that interfaces with access networks,including Gigabit Ethernet over fiber networks, SONET OC-n networks, andothers. It is an object of the invention to provide wavelengthconversion at such an interface for wavelengths of such access networksthat are not compliant with the optical network.

The invention utilizes particular decompositions of a node's opticalswitching hardware in achieving these and other aspects of theinvention. A node of an optical network in accordance with the presentinvention is also referred to as an optical transport switching system(or simply an “OTS”).

In one aspect of the invention, a node includes an optical accessingress subsystem, an optical access egress subsystem a transportingress subsystem, a transport egress subsystem, and an optical switchsubsystem. The optical switch subsystem selectively provides opticalcoupling between (a) the transport egress subsystem and at least one of(a)(1) the optical access ingress subsystem and (a)(2) the transportingress subsystem, and between (b) the transport ingress subsystem andat least one of one of (b)(1) the optical access egress subsystem, and(b)(2) the transport egress subsystem.

In another aspect of the invention, a node includes a chassis having aplurality of receiving locations, where at least some of the receivinglocations are adapted to receive optical circuit cards. Moreover, anoptical backplane is associated with the chassis for providing selectiveoptical coupling between the optical circuit cards, and a local areanetwork enables control and monitoring of the optical circuit cards by acentral controller.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the figures of the accompanyingdrawings, which are meant to be exemplary, and not limiting, in whichlike references are intended to refer to like or correspondingstructures, and in which:

FIG. 1 illustrates an all-optical network architecture in accordancewith the present invention;

FIG. 2 illustrates a logical node architecture in accordance with thepresent invention;

FIG. 3 illustrates an optical transport switching system hardwarearchitecture in accordance with the present invention;

FIG. 4 illustrates a control architecture for an OTS in accordance withthe present invention;

FIG. 5 illustrates a single Node Manager architecture in accordance withthe present invention;

FIG. 6 illustrates a Line Card Manager architecture in accordance withthe present invention;

FIG. 7 illustrates an OTS configuration in accordance with the presentinvention;

FIG. 8 illustrates backplane Ethernet hubs for an OTS in accordance withthe present invention;

FIG. 9 illustrates the operation of a control architecture and OpticalSignaling Module in accordance with the present invention;

FIG. 10 illustrates an optical switch fabric module in accordance withthe present invention;

FIG. 11 illustrates a Transport Ingress Module in accordance with thepresent invention;

FIG. 12 illustrates a Transport Egress Module in accordance with thepresent invention;

FIG. 13 illustrates an Optical Access Ingress module in accordance withthe present invention;

FIG. 14 illustrates an Optical Access Egress module in accordance withthe present invention;

FIG. 15 illustrates a Gigabit Ethernet Access Line Interface module inaccordance with the present invention;

FIG. 16 illustrates a SONET OC-12 Access Line Interface module inaccordance with the present invention;

FIG. 17 illustrates a SONET OC-48 Access Line Interface module inaccordance with the present invention;

FIG. 18 illustrates a SONET OC-192 Access Line Interface module inaccordance with the present invention;

FIG. 19 illustrates an Optical Performance Monitoring module inaccordance with the present invention;

FIG. 20 illustrates a physical architecture of an OTS chassis in an OXCconfiguration in accordance with the present invention;

FIG. 21 illustrates a physical architecture of an OTS chassis in anOXC/OADM configuration in accordance with the present invention;

FIG. 22 illustrates a physical architecture of an OTS chassis in an ALIconfiguration in accordance with the present invention;

FIG. 23 illustrates a full wavelength cross-connect configuration inaccordance with the present invention;

FIG. 24 illustrates an optical add/drop multiplexer configuration withcompliant wavelengths in accordance with the present invention;

FIG. 25 illustrates an optical add multiplexer configuration inaccordance with the present invention;

FIG. 26 illustrates an optical drop multiplexer configuration inaccordance with the present invention;

FIG. 27 illustrates an example data flow through optical switches,including add/drop multiplexers and wavelength cross-connects, inaccordance with the present invention;

FIG. 28 illustrates Gigabit Ethernet networks accessing a managedoptical network in accordance with the present invention;

FIG. 29 illustrates SONET networks accessing a managed optical networkin accordance with the present invention;

FIG. 30 illustrates a hierarchical optical network structure inaccordance with the present invention;

FIG. 31 illustrates a system functional architecture in accordance withthe present invention;

FIG. 32 illustrates network signaling in accordance with the presentinvention;

FIGS. 33( a)–(c) illustrate a normal data flow, a data flow with lineprotection, and a data flow with path protection, respectively, inaccordance with the present invention;

FIG. 34 illustrates a high-level Network Management System functionalarchitecture in accordance with the present invention;

FIG. 35 illustrates a Network Management System hierarchy in accordancewith the present invention;

FIG. 36 illustrates a Node Manager software architecture in accordancewith the present invention;

FIG. 37 illustrates a Protection/Fault Manager context diagram inaccordance with the present invention;

FIG. 38 illustrates a UNI Signaling context diagram in accordance withthe present invention;

FIG. 39 illustrates a NNI Signaling context diagram in accordance withthe present invention;

FIG. 40 illustrates an NMS Database/Server Client context diagram inaccordance with the present invention;

FIG. 41 illustrates a Routing context diagram in accordance with thepresent invention;

FIG. 42 illustrates an NMS Agent context diagram in accordance with thepresent invention;

FIG. 43 illustrates a Resource Manager context diagram in accordancewith the present invention;

FIG. 44 illustrates an Event Manager context diagram in accordance withthe present invention;

FIG. 45 illustrates a Software Version Manager context diagram inaccordance with the present invention;

FIG. 46 illustrates a Configuration Manager context diagram inaccordance with the present invention;

FIG. 47 illustrates a Logger context diagram in accordance with thepresent invention;

FIG. 48 illustrates a Flash Interface context diagram in accordance withthe present invention; and

FIG. 49 illustrates a Line Card Manager software process diagram inaccordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detailwith reference to the accompanying figures.

A Glossary is provided at the end of the following description, whereincertain terms and acronyms are defined.

1. OTS Overview

The present invention provides for an all optical configurable switch(i.e., network node or OTS) that can operate as an optical cross-connect(OXC) (also referred to as a wavelength cross-connect, or WXC), whichswitches individual wavelengths, and/or an optical add/drop multiplexer(OADM). The switch is typically utilized with a Network ManagementSystem also discussed herein.

As an all-optical switching system, the switch of the present inventionoperates independently of bit rates and protocols. Typically, theall-optical switching, between inputs and outputs of the OTS, isachieved through the use of Micro-Electro-Mechanical System (MEMS)technology. Moreover, this optical switch offers an on-demand λswitching capability to support, e.g., either SONET ring based or meshconfigurations.

The OTS also provides the capability to achieve an optimized networkarchitecture since multiple topologies, such as ring and mesh, can besupported. Thus, the service provider can tailor its network design tobest meet its traffic requirements. The OTS also enables flexible accessinterconnection supporting SONET circuits, Gigabit Ethernet (GbE) (IEEE802.3z), conversion from non-ITU compliant optical wavelengths, andITU-compliant wavelength connectivity. With these interfaces, theservice provider is able to support a broad variety of protocols anddata rates and ultimately provide IP services directly over DWDM withoutSONET equipment. The OTS further enables a scalable equipmentarchitecture that is provided by a small form factor and modular designsuch that the service provider can minimize its floor space and powerrequirements needs and thereby incrementally expand its network withinthe same footprint.

FIG. 1 illustrates an all-optical “metro core” network architecture thatutilizes the present invention in accordance with a variety ofconfigurations.

OTS equipment is shown within the optical network boundary 105, and isdesigned for deployment both at the edges of a metro core network (whenoperating as an OADM), and internally to a metro core network (whenoperating as an OXC). For example, the OTSs at the edge of the networkinclude OADMs 106, 108, 110 and 112, and the OTSs internal to thenetwork include WXCs 115, 117, 119, 121 and 123. Each OTS is a node ofthe network.

External devices such as SONET and GbE equipment may be connecteddirectly to the optical network 105 via the edge OTSs. For example,SONET equipment 130 and 134, and GbE equipment 132 connect to thenetwork 105 via the OADM 106. GbE 136 and SONET 138 equipment connect tothe network via OADM 108. GbE 140 and SONET equipment 142 and 144connect to the network via OADM 110. SONET equipment 146 connects to thenetwork via OADM 112. The network architecture may also support othernetwork protocols as indicated, such as IP, MPLS, ATM, and Fibre Channeloperating over the SONET and GbE interfaces.

FIG. 2 depicts a logical node architecture 200, which includes anOptical Switch Fabric 210, Access Line Interface 220, Optical AccessIngress 230, Optical Access Egress 235, Transport Ingress 240, andTransport Egress 245 functions. These functions (described below) areimplemented on respective line cards, also referred to as opticalcircuit cards or circuit packs or packages, that are receivable ordeployed in a common chassis. Moreover, multiple line cards of the sametype may be used at an OTS to provide scalability as the bandwidth needsof the OTS grow over time.

A Node Manager 250 and Optical Performance Monitoring (OPM) module 260may also be implemented on respective line cards in the chassis. NodeManager 250 typically communicates with the rest of the OTS 200 througha 100 BaseT Ethernet internal LAN distributed to every line card andmodule and terminated by the Line Card Manager module 270 residing onevery line card. Alternatively, a selectable 10/100 BaseT connection maybe used. OPM 260 is responsible for monitoring optical hardware of OTS200, and typically communicates its findings to the Node Manager 250 viathe internal LAN and the OPM's LCM. The Node manager may process thisperformance information to determine whether the hardware is functioningproperly. In particular, based on the OPM information, the Node Managermay apply control signals to the line cards, switchover to backupcomponents on the line cards or to backup line cards, set alarms for theNMS, or take other appropriate action.

Each of the line cards, including the OPM 260 and the line cards thatcarry the optical signals in the network, shown within the dashed line265, are controlled by respective LCMs 270. The Node Manager 250 maycontrol the line cards, and receive data from the line cards, via theLCMs 270.

Being interfaced to all other cards of the OTS 200 via the internal LANand LCMs, the Node Manager 250 is responsible for the overall managementand operation of the OTS 200 including signaling, routing, and faultprotection. The responsibility for telemetry of all control and statusinformation is delegated to the LCMs. There are also certain localfunctions that are completely abstracted away from the Node Manager andhandled solely by the LCMs, such as laser failsafe protection. Whenevera light path is created between OTSs, the Node Manager 250 of each OTSperforms the necessary signaling, routing and switch configuration toset up the path. The Node Manager 250 also continuously monitors switchand network status such that fault conditions can be detected, isolated,and repaired. The OPM 260 may be used in this regard to detect a loss ofsignal or poor quality signal, or to measure signal parameters such aspower, at any of the line cards using appropriate optical taps andprocessing circuitry. Three levels of fault recovery may be supported:(1) Component Switchover—replacement of failed switch components withbackup, (2) Line Protection—rerouting of all light paths around a failedlink; and (3) Path Protection—rerouting of individual light pathsaffected by a link or node failure. Component Switchover is preferablyimplemented within microseconds, while Line Protection is preferablyimplemented within milli-seconds of failure, and Path Restoration maytake several seconds.

The all-optical switch fabric 210 is preferably implemented using MEMStechnology. However, other optical switching components may be used,such as lithium niobate modules, liquid crystals, bubbles andthermo-optical switching technologies. MEMS have arrays of tiny mirrorsthat are aimed in response to an electrostatic control signal. By aimingthe mirrors, any optical signal from an input fiber (e.g., of atransport ingress or optical access ingress line card) can be routed toany output fiber (e.g., of a transport egress or optical access egressline card).

The Optical Access Network 205 may support various voice and dataservices, including switched services such as telephony, ISDN,interactive video, Internet access, videoconferencing and businessservices, as well as multicast services such as video. Service providerequipment in the Optical Access Network 205 can access the OTS 200 intwo primary ways. Specifically, if the service provider equipmentoperates with wavelengths that are supported by the OTS 200 of theoptical network, such as selected OC-n ITU-compliant wavelengths, it candirectly interface with the Optical Access (OA) ingress module 230 andegress module 235. Alternatively, if the service provider equipment isusing a non-compliant wavelength, e.g., in the 1310 nm range, or GbE (or10 GbE), then it accesses the OTS 200 via an ALI card 220.Advantageously, since a GbE network can be directly bridged to the OTSwithout a SONET Add/Drop Multiplexer (ADM) and a SONET/SDH terminal,this relatively more expensive equipment is not required, so serviceprovider costs are reduced. That is, typically, legacy electronicinfrastructure equipment is required to connect with a SONET terminatorand add-drop multiplexer (ADM). In contrast, these functions areintegrated in the OTS of the present invention, resulting in good costbenefits and a simpler network design. In other words, because the GbEphysical layer is a substitute for the SONET physical layer, and becausethere is no reason to stack two physical layers, the SONET equipmentwould be redundant. Table 1 summarizes the access card interfaceparameters associated with each type of OA and ALI card, in somepossible implementations.

TABLE 1 Data Card Protocol Rate Type External Ports Internal PortsITU-Compliant OC-12 OA 8 OC-12 8 OC-12 SONET OC-48 OA 8 OC-48 8 OC-48OC-192 OA 8 OC-192 8 OC-192 Non-Compliant OC-12 ALI 8 OC12 Input 2 OC48Output SONET 8 OC12 Output 2 OC48 Input OC-48 ALI 8 OC48 Input 2 OC192Output 8 OC48 Output 2 OC192 Input OC-192 ALI 2 OC192 Input 2 OC192Output 2 OC192 Output 2 OC192 Input Gigabit Ethernet 1 Gbps ALI 8 GbEInput 2 OC48 Output 8 GbE Output 2 OC48 Input

The OTS can interface with all existing physical and data-link layerdomains (e.g., ATM, IP router, Frame relay, TDM, and SONET/SDH/STMsystems) so that legacy router and ATM systems can connect to the OTS.The OTS solution also provides the new demand services, e.g.,audio/video on demand, with cost-effective bandwidth and efficientbandwidth utilization.

The OTS 200 can be configured, e.g., for metro and long haulconfigurations. In one possible implementation, the OTS can be deployedin up to four-fiber rings, up to four fiber OADMs, or four fiberpoint-to-point connections. Each OTS can be set to add/drop anywavelength with the maximum of sixty-four channels of local connections.

2. Hardware Architecture

FIG. 3 illustrates an OTS hardware architecture in accordance with thepresent invention. The all-optical switch fabric 210 may include eight8×8 switch elements, the group of eight being indicated collectively as211. Each of the eight switch elements is responsible for switching anoptical signal from each of eight sources to any one of eight outputs.

Generally, selected outputs of the TP ingress cards 240 and OA ingresscards 230 are optically coupled by the switching fabric cards 210 toselected inputs of the TP egress cards 245 and/or OA egress cards 235.The optical coupling between cards and the fabric occurs via an opticalbackplane, which may comprise optical fibers. Preferably, the cards areoptically coupled to the optical backplane when they are inserted intotheir slots in the OTS bay such that the cards can be easily removed andreplaced. For example, MTP™-type connectors (Fiber Connections, Inc.)may be used. This allows easy troubleshooting and upgrading of cards.Moreover, each line card may connect to an RJ-45 connector when insertedinto their slots.

Moreover, each TP ingress and OA ingress card has appropriate opticaloutputs for providing optical coupling to inputs of the switch fabricvia the optical backplane. Similarly, each TP egress and OA egress cardhas appropriate optical inputs for providing optical coupling to outputsof the switch fabric via the optical backplane. With appropriate controlsignals, the switching fabric is controlled to optically couple selectedinputs and outputs of the switch fabric card, thereby providingselective optical coupling between outputs of the TP ingress and OAingress cards, and the inputs of the TP egress and OA egress cards. As aresult, the optical signals carried by the outputs of TP ingress and OAingress cards can be selectively switched (optically coupled) to theinputs of the TP egress and OA egress cards.

In the example configuration shown in FIG. 3, the transport ingressmodule 240 includes four cards 302, 304, 306 and 308, each of whichincludes a wavelength division demultiplexer (WDD), an example of whichis the WDD 341, for recovering the OSC, which may be provided as anout-of-band signal with the eight multiplexed data signals (λ's).

An optical amplifier (OA), an example of which is the OA 342, amplifiesthe optical transport signal multiplex, and a demux, an example of whichis the demux 343, separates out each individual wavelength (opticaltransport signal) in the multiplex. Each individual wavelength isprovided to the switch fabric 210 via the optical backplane, thenswitched by one of the modules 211 thereat. The outputs of the switchfabric 210 are provided to the optical backplane, then received byeither a mux, an example of which is the mux 346, of one of thetransport egress cards 320, 322, 324 or 326, or an 8×8 switch of one ofthe OA egress cards 235. At each of the TP egress cards, the multiplexeroutput is amplified at the associated OA, and the input OSC ismultiplexed with data signals via the WDM. The multiplexer output at theWDM can then be routed to another OTS via an optical link in thenetwork. At the OA egress cards 235, each received signal is amplifiedand then split at 1×2 dividers/splitters to provide correspondingoutputs either to the faceplate of the OA egress cards for compliantwavelengths, or to the ALI cards via the optical backplane fornon-compliant wavelengths. Note that only example light paths are shownin FIG. 3, and that for clarity, all possible light paths are notdepicted.

The ALI cards perform wavelength conversion for interfacing with accessnetworks that use optical signals that are non-compliant with the OTS.As an example, the ALI card receives non-compliant wavelength signals,converts them to electrical signals, multiplexes them, and generates acompliant wavelength signal. Two optical signals that are output fromthe ALI card 220 are shown as inputs to one of the OA_(—)In cards 230 tobe transmitted by the optical network, and two optical signals that areoutput from one of the OA_(—)Eg cards 235 are provided as inputs to theALI cards 220. N total inputs and outputs (e.g., N=4, two inputs and twooutputs) may be input to, or output from, the ALI cards 220.

The OSC recovered at the TP ingress cards, namely OSC_(OUT), isprocessed by the Optical Signaling Module (OSM) of the OTS using an O-Econversion. The OSM generates a signaling packet that contains signalingand route information, and passes it on to the Node Manager. The OSM isdiscussed further below, particularly in conjunction with FIG. 9. If theOSC is intended for use by another OTS, it is re-generated by the OSMfor communication to another OTS and transmitted via, e.g., OSC_(IN).Or, if the OSC is intended for use only by the present OTS, there is noneed to relay it to a further node. Alternatively, OSC_(IN) could alsorepresent a communication that originated from the present OTS and isintended for receipt, e.g., by another node. For a group of nodesoperating under the control of an NMS, typically only one of the nodesacts as a gateway to the shared NMS. The other nodes of the groupcommunicate with the NMS via the gateway node and communication by theother nodes with their gateway node is typically also accomplished viathe OSC.

FIG. 4 illustrates a control architecture for an OTS in accordance withthe present invention. The OTS implements the lower two tiers of theabove described three-tier control architecture typically without atraditional electrical backplane or shelf controller. Moreover, the OTShas a distributed architecture, which results in maximum systemreliability and stability. The OTS does not use a parallel backplane bussuch as Compact PCI or VME bus because they represent a single point offailure risk, and too much demand on one shared element is a performancerisk. Instead, the invention preferably provides a distributedarchitecture wherein each line card of the OTS is outfitted with atleast one embedded controller referred to as a LCM on at least onedaughter board, with the daughter boards communicating with the node'ssingle Node Manager via a LAN technology such as 100 BaseT Ethernet andCore Embedded Control Software.

In particular, the LCM may use Ethernet layer 2 (L2) datagrams forcommunication with the Node Manager, with the Node Manager being thehighest-level processor within an individual OTS. The Node Manager andall OTS line cards plug into a 100 BaseT port on one or more hubs viaRJ-45 connectors to allow electronic signaling between LCMs and the NodeManager via an internal LAN at the OTS. In a particular embodiment, twotwenty-four port hubs are provided to control two shelves of line cardsin an OTS bay, and the different hubs are connected by crossover cables.For example, FIG. 4 depicts LCMs 410 and associated line cards 420 asconnected to hubs 415 and 418, which may be 24-port 100 BaseT hubs. Theline cards may perform various functions as discussed, including GigabitEthernet interface (a type of ALI card), SONET interface (a type of ALIcard), TP ingress, TP egress, optical access ingress, optical accessegress, switching fabric, optical signaling, and optical performancemonitoring.

Moreover, while only one Node Manager is required, the primary NodeManager 250 can be provided with a backup Node Manager 450 forredundancy. Each Node Manager has access to the non-volatile data on theLCMs which help in reconstructing the state of the failed node manager.The backup Node Manager gets copies of the primary node managernon-volatile store, and listens to all traffic (e.g., messages from theLCMs and the primary Node Manager) on all hubs in the OTS to determineif the primary has failed. Various schemes may be employed fordetermining if the primary Node Manager is not functioning properly,e.g., by determining whether the primary Node Manager 250 responds to amessage from an LCM within a specified amount of time.

In particular, the hubs 415 and 418 are connected to one another via acrossover 417 and additional hubs may also be connected in this manner.See also FIG. 8. In terms of the OTS bay, every shelf connects to a 100BaseT hub. This use of an Ethernet backplane provides bothhot-swappability of line cards (i.e., removal and insertion of linecards into the OTS bay when optical and/or electrical connections areactive), and totally redundant connections between the line cards andboth Node Managers. Moreover, if the node is a gateway, its primary NodeManager communicates with the NMS, e.g., via a protocol such as SNMP,using 100 BaseT ports 416, 419. Alternatively, selectable 10/100 BaseTmay be used. RJ-45 connectors on the faceplate of the Node Managercircuit pack may be used for this purpose.

The Node Manager and Line Card Manager are described further, below.

3. Node Manager Module

FIG. 5 illustrates a single Node Manager architecture 250 in accordancewith the present invention. An OTS with primary and backup Node Managerswould have two of the architectures 250.

The Node Manager executes all application software at the OTS, includingnetwork management, signaling, routing, and fault protection functions,as well as other features.

As discussed above, each Node Manager circuit pack has a 100 BaseTnetwork connection to a backplane hub that becomes the shared medium foreach LCM in the OTS. Additionally, for a gateway OTS node, another 100BaseT interface to a faceplate is provided for external network access.

The Node Manager Core Embedded Software performs a variety of functions,including: i) issuing commands to the LCMs, ii) configuring the LCMswith software, parameter thresholds or other data, iii) reportingalarms, faults or other events to the NMS, and iv) aggregating theinformation from the LCMs into a node-wide view that is made availableto applications software at the Node Manager. This node-wide view, aswell as the complete software for each LCM controller, are stored inflash memory 530. The node- or switch-wide view may provide informationregarding the status of each component of the switch, and may include,e.g., performance information, configuration information, softwareprovisioning information, switch fabric connection status, presence ofalarms, and so forth. Since the node's state and the LCM software arestored locally to the node, the Node Manager can rapidly restore aswapped line card to the needed configuration without requiring a remotesoftware download, e.g., from the NMS.

The Node Manager is also responsible for node-to-node communicationsprocessing. All signaling messages bound for a specific OTS are sent tothe Node Manager by that OTS's optical signaling module. The OSM, whichhas an associated LCM, receives the OSC wavelength from the TransportIngress module. The incoming OSC signal is converted from optical toelectrical, and received as packets by the OSM. The packets are sent tothe Node Manager for proper signaling setup within the system. On theoutput side, out-going signaling messages are packetized and convertedinto an optical signal of, e.g., 1310 nm or 1510 nm, by the OSM, andsent to the Transport Egress module for transmission to the next-hopOTS. The Node Manager configures the networking capabilities of the OSM,e.g., by providing the OSM with appropriate software for implementing adesired network communication protocol.

The Node Manager may receive remote software downloads from the NMS toprovision itself and the LCMs. The Node Manager distributes each LCM'ssoftware via the OTS's internal LAN, which is preferably a shared mediumLAN. Each LCM may be provisioned with only the software it needs formanaging the associated line card type. Or, each LCM may be provisionedwith multi-purpose software for handling any type of line card, wherethe appropriate software and/or control algorithms are invoked after anLCM identifies the line card type it is controlling (e.g., based on theLCM querying its line card or identifying its slot location in the bay).

In one possible implementation, the Node Manager uses a main processor505, such as the 200 MHz MPC 8255 or MPC8260 (Motorola PowerPCmicroprocessor, available from Motorola Corp., Schaumburg, Illinois),with an optional plug-in module 510 for a higher power plug-in processor512, which may be a RISC CPU such as the 400 MHz MPC755. Theseprocessors 505, 510 simultaneously support Fast Ethernet, 155 Mbps ATMand 256 HDLC channels. However, the invention is not limited to use withany particular model of microprocessor. Moreover, while the plug-inmodule 510 is optional, it is intended to provide for a longer usefullife for the Node Manager circuit pack by allowing the processor to beupgraded without changing the rest of the circuit pack.

The Node Manager architecture is intended to be flexible in order tomeet a variety of needs, such as being a gateway and/or OTS controller.The architecture is typically provided with a communications modulefront end that has two Ethernet interfaces: 1) the FCC2 channel 520,which is a 100 BaseT to service the internal 100 BaseT Ethernet hub onthe backplane 522, and, for gateway nodes, 2) the FCC3 channel 525,which is a 100 BaseT port to service the NMS interface to the outside.The flash memory 530 may be 128 MB organized in a×16 array, such that itappears as the least significant sixteen data bits on the bus 528. Seethe section entitled “Flash Memory Architecture” for further informationregarding the flash memory 530.

The bus 528 may be an address and data bus, such as Motorola's PowerPC60×. The SDRAM 535 may be 256 MB organized by sixty-four data bits. AnEPROM 532 may store start up instructions that are loaded into theprocessor 505 or 512 via the bus 528 during an initialization or resetof the Node Manager. A PCMCIA Flash disk 537 also communicates with thebus 528, and is used for persistent storage, e.g., for storing long termtrend data and the like from monitored parameters of the line cards. Awarning light may be used so that the Flash disk is not inadvertentlyremoved while data is being written to it. Preferably, to preventtampering, the non-volatile memory resources, such as the Flash disk,are designed so that they cannot be removed while the Node Manager cardis installed on the OTS backplane.

Additionally, there is a SDRAM 540 (e.g., having 4 MB) on the local bus545, which is used to buffer packets received on the communicationsmodule front-end of the main processor 505. The local bus 545 may carryeighteen address bits and thirty-two data bits.

Flexibility is promoted if the core microprocessor (such as is possiblewith Motorola's PowerPC 603 e core inside the MPC8260) 505 can bedisabled, and the plug-in processor 512 can be installed on the bus 528.Such plug-in processor 512 can be further assisted with an L2 backsidecache 514, e.g., having 256 KB. It is expected that a plug-in processorcan be used to increase the performance of the Node Manager 505 by morethan double. As an example, the plug-in processor 512 may be any futuretype of RISC processor that operates on the 60× bus. The processor 505yields the bus to, and may also align its peripherals to, the morepowerful plug-in processor 512. In addition to providing a generalpurpose path for upgradability of the Node Manager, the plug-inprocessor is also useful, e.g., for the specific situation where the OTShas had line cards added to it and the main processor 505 is thereforeno longer able to manage its LCMs at a rate compatible with the desiredperformance characteristics of the optical networking system.

A serial port 523 for debugging may also be created.

In summary, the Node Manager provides NMS interface and local nodemanagement, as well as providing signaling, routing and fault protectionfunctions (all using the Node Manager's application software), providesreal-time LCM provisioning, receives monitored parameters andalarms/faults from each LCM, aggregates monitored parameters andalarms/faults from each line card into a node-wide view, processesnode-to-node communication messages, provides remote software downloadcapability, distributes new software to all LCMs, is expandable toutilize a more powerful CPU (through plug-in processor 512), such as ofRISC design, is built on a Real-Time Operating System (RTOS), providesintra-OTS networking support (e.g., LAN connectivity to LCMs), andprovides node-to-node networking support.

4. Line Card Manager Module

FIG. 6 illustrates a Line Card Manager architecture 600 in accordancewith the present invention. As discussed above, the LCM modules may beprovided as daughter boards/plug-in modules that plug into therespective line cards to control each line card in the OTS. The LCMsoffload local processing tasks from the Node Manager and providecontinued line card support without any interruptions in the event theNode Manager fails (assuming no backup is available, or the backup hasalso failed), or the communication path to the Node Manager is notavailable. That is, even if the control path is lost, the user datapaths are still active. The line card state and data are stored untilthe Node Manager is back in service. This is made possible by theloosely coupled distributed architecture which allows the LCM to actindependently of the Node Manager whenever necessitated by failure ofthe Node Manager. The parameters which keep the line card active arekept locally on the LCM, thus allowing the line card to actindependently of the Node Manager for a time. The Node Manager can bereplaced while the OTS continues to function.

The line cards which an LCM 600 may control include any of thefollowing: switch fabric, TP_(—)IN, TP_(—)EG, OA_(—)IN, OA_(—)EG, OSM,OPM, or ALI cards (acronyms defined in Glossary).

The LCM daughter board is built around an embedded controller/processor605, and contains both digital and analog control and monitoringhardware. LCMs typically communicate with the Node Manager via the OTSinternal LAN. The LCM receives commands from the Node Manager, such asfor configuring the line cards, and executes the commands via digitaland analog control signals that are applied to the associated line card.The LCM gathers from its line card digital and analog feedback andmonitored parameter values, and may periodically send this informationto the Node Manager, e.g., if requested by the Node Manager. The LCMalso passes events such as faults/alarms and alerts to the Node Manageras they occur. These values and all provisioning data are kept in anin-memory snapshot of the line card status.

Preferably, the LCM stores this snapshot and a copy of the software thatis currently running the LCM in its non-volatile (e.g., flash) memory610 to allow rapid rebooting of the LCM. Specifically, when the LCMpowers up, it loads the software from the non-volatile memory 610 intoSDRAM 625, and then begins to execute. This avoids the need for the LCMto download the software from the Node Manager via the OTS internal LANeach time it starts up, which saves time and avoids unnecessary trafficon the internal OTS LAN. The software logic for all line cards ispreferably contained in one discrete software load which has the abilityto configure itself based on the identity of the attached line card asdisclosed during the discovery phase of LCM initialization. The type ofline card may be stored on an EEPROM on the line card. The LCM queriesthe EEPROM through the I²C bus to obtain the identifier.

See the section entitled “Flash Memory Architecture” for furtherinformation regarding the flash memory 610.

The LCM can also receive new software from the Node Manager via the OTSinternal LAN and store it in the flash memory 610. It is desirable tohave sufficient non-volatile memory at the LCM to store two copies ofthe software, i.e., a current copy and a backup copy. In this way, a newsoftware version, e.g., that provides new features, could be stored atthe LCM and tested to see if it worked properly. If not, the backup copy(rollback version) of the previous software version could be used.

The Node Manager delegates most of the workload for monitoring andcontrolling the individual line cards to each line card's local LCM.This reduces the central point of failure threat posed by a centralizedarchitecture, increasing the probability that the optical network cankeep functioning, even if levels of control above the LCM (i.e., theNode Manager or NMS) were to suffer a failure. Distributed architecturesalso scale better since, as each line card is added, at least onededicated processor daughter board (i.e., the LCM) is added to controlit. In one possible implementation, the controller 605 is the 200 MHzMotorola MPC8255 or MPC8260. However, the invention is not limited touse with any particular model of microprocessor. The controller 605 mayhave a built-in communications processor front-end, which includes anEthernet controller (FCC2) 615 that connects to the Node Manager via theinternal switch LAN. In the embodiment shown, this connection is madevia the line card using an RJ-45 connector. Other variations arepossible.

The flash memory 610 may be 128 MB organized in ×16 mode, such that itappears as the least significant sixteen data bits on the bus 620, whichmay be Motorola's 60× bus. The SDRAM 625 may be 64 MB organized bysixty-four data bits. An A/D converter 635, such as the AD7891-1 (AnalogDevices, Inc., Norwood, Mass.) includes a 16 channel analog multiplexerinto a 12 bit A/D converter. A D/A converter 622, which may be an arrayof four “quad” D/A converters, such as MAX536's (Maxim IntegratedProducts, Inc., Sunnyvale, Calif.), provides sixteen analog outputs to aconnector 640, such as a 240-pin Berg Mega-Array connector (BergElectronics Connector Systems Ltd, Herts, UK). The LCMs and line cardspreferably adhere to a standard footprint connect scheme so that it isknown which pins of the connector are to be driven or read. Essentially,a telemetry connection is established between the LCM and the line cardvia the connector 640.

Advantageously, since the LCM can be easily removed from its line cardinstead of being designed into the line card, it can be easily swappedwith an LCM with enhanced capabilities, e.g., processor speed andmemory, for future upgrades.

The LCM daughter board removeably connects to the associated line cardvia a connector 640. A serial port 645 for debugging may be added. Forthe MPC8255 or MPC8260, such a serial port 645 may be constructed fromport D (SMC1). There is typically a 4 MB SDRAM 650 on the Local Bus 655,which is used to buffer packets received on the communications modulefront-end of the controller 605. Port A 636 receives a latch signal.

A serial bus known as a Serial Peripheral Interface SPI 606 isspecialized for A/D and D/A devices, and is generated by the controller605. It is a three-wire SPI for transmitted data, received data, andclock data that may be used with the more complicated line cards thathave many registers and inputs/outputs. Examples of such morecomplicated line cards may be the OC-n and GbE ALI cards and theswitching fabric line cards. Essentially, the SPI 606 provides aninterface that allows a line card to communicate directly with thecontroller 605. The SPI 606 may carry analog signals to the line cardvia the D/A 622, or receive analog signals from the line card via theA/D 635.

The FPGA 602 provides a 40-bit status read only register for reading insignals from the line card, and a 32 bit read/write control register forreading/writing of control signals from/to the line card. Theseregisters may be addressed via a GPIO on the connector 640. The FPGA 602also receives an 8-bit line card ID tag that identifies the location ofthe line card within the OTS (i.e., slot, shelf and bay) since certainslots are typically reserved for certain line card types. The slotlocations are digitally encoded for this purpose. Alternatively, or inaddition, the type of line card could be identified directly regardlessof the slot, shelf and bay, e.g., by using a serial number or otheridentifier stored on the line card and accessible to the LCM, e.g., viaan I²C bus 604. This bus enables the communication of data between thecontroller 605 and the connector 640. In particular, the bus 604 may bepart of a GPIO that receives information from a line card, including thebay, shelf and slot, that identifies the line card's position at theOTS.

The controller 605 may receive a hard reset signal from the NodeManager, e.g., via the Ethernet controller (FCC2) 615, which clears allregisters and performs a cold boot of the system software on the LCM,and a soft reset signal, which performs a warm boot that does notinterfere with register contents. The soft reset is preferred forpreserving customer cross connect settings.

To fulfill the mission of the Node Manager as an abstraction/aggregationof the LCM primitives, the LCM is preferably not accessible directlyfrom the customer LAN/WAN interfaces.

An EPROM 612, e.g., having 8 KB, may store instructions that are loadedinto the processor 605 via the bus 620 during an initialization or resetof the LCM.

The microcontroller 605 typically integrates the following functions:603 e core CPU (with its non-multiplexed 32 bit address bus andbi-directional 64 bit data bus), a number of timers (including watchdogtimers), chip selects, interrupt controller, DMA controllers, SDRAMcontrols, and asynchronous serial ports. The second fast communicationchannel (FCC2) 100 BaseT Ethernet controller is also integrated into theCommunications Processor Module functions of the controller 605. Themicrocontroller may be configured for 66 Mhz bus operation, 133 Mhz CPMoperation, and 200 Mhz 603 e core processor operation.

In summary, the line card manager module provides local control for eachline card, executes commands received from the Node Manager, providesdigital and/or analog control and monitoring of the line card, sendsmonitored parameters and alarms/faults of the line card to the NodeManager, provides an embedded controller with sufficient processingpower to support a RTOS and multi-tasking, and provides Intra-OTSnetworking support.

5. OTS Configuration

FIG. 7 illustrates an OTS configuration in accordance with the presentinvention.

The OTS 700 includes an optical backplane 730 that uses, e.g., opticalfibers to couple optical signals to the different optical circuit cards(line cards). Preferably, specific locations/slots of the chassis arereserved for specific line card types according to the required opticalinputs and outputs of the line card. Moreover, the optical backplane 730includes optical connections to optical links of the optical network,and, optionally, to links of one or more access networks.

Furthermore, while one of each line card type is shown, as notedpreviously, more than one line card of each type is typically providedin an OTS configuration.

Each of the optical circuit cards (specifically, the LCMs of the cards)also communicates via a LAN with the Node Manager to enable the controland monitoring of the line cards.

The optical inputs and outputs of each card type are as follows:

ALI—inputs an from access network link and OA egress cards; outputs toan access network link and OA ingress cards;

OA ingress cards—inputs from an access network link and ALI cards;outputs to switching fabric cards and OPM cards;

OA egress cards—inputs from switching fabric cards; outputs to ALIcards, OPM cards, and an access network link;

TP ingress cards—inputs from an optical network link; outputs toswitching fabric cards and OPM cards;

TP egress cards—inputs from switching fabric cards; outputs to anoptical network link and OPM cards;

Switch fabric cards—inputs from OA ingress cards and TP ingress cards;outputs to OA egress cards and TP egress cards;

OSM—inputs from TP ingress cards; outputs to TP egress cards; and

OPM—inputs from TP ingress cards, TP egress cards, OA ingress cards, andOA egress cards (may monitor additional cards also).

6. Interconnected Backplane Ethernet Hubs

FIG. 8 illustrates backplane Ethernet hubs for an OTS in accordance withthe present invention. The OTS may use standard Ethernet hub assemblies,such as 24-port hubs 830 and 840, to form the basis of inter-processorcommunication (i.e., between the Node Manager and the LCMs). Each hubassembly 830, 840 may have, e.g., twenty-four or more ports, whereas thecorresponding shelf backplanes (815, 825, 835, 845, respectively)typically have, e.g., 6–8 ports. A number of connectors, two examples ofwhich are denoted at 820, are provided to enable each line card toconnect to a hub. The connectors may be RJ-45 connectors. The dashedlines denote a conceptual electrical connection from the connectors 820to one or more of the hubs. Typically, each connector 820 is connectedindividually to a hub. For example, the connectors for shelf 1 (815) andshelf 3 (835) may connect to hub 830, while the connectors for shelf 2(825) and shelf 4 (845) may connect to hub 840. Moreover, a crossovercable 842, which may be a cable such as 100 BaseT media, may connect thetwo hubs such that they are part of a common LAN. Other variations arepossible. For example, a single hub may be used that is sized largeenough to connect to each line card in the OTS bay.

In this arrangement, the backup Node Manager 750 shadows the primaryNode Manager 250 by listening to all traffic on the internal OTSbackplane hubs (the shared media LAN), to determine when the primaryNode Manager ceases to operate. When such a determination is made, thebackup Node Manager takes over for the primary Node Manager 750.

7. Optical Signaling Module

FIG. 9 illustrates the operation of a control architecture and OSM inaccordance with the present invention. The OSM provides an IP signalingnetwork between switches for the interchange of signaling, routing andcontrol messages. A gateway node 900 can interact with other networks,and includes an intra-product (internal to the OTS) LAN 905, whichenables communication between the Node Manager 910 and the LCMs, such asLCM 916 and the associated line card 915, . . . , LCM 918 and theassociated line card 917, and LCM 921 and the associated line card 920,which is an OSM. An example non-gateway node 950 similarly includes anintra-product LAN 955, which enables communication between its NodeManager and the LCMs, such as LCM 966 and the associated line card 965,. . . , LCM 968 and the associated line card 967, and LCM 971 and theassociated line card 970, which is an OSM.

The OSC wavelength from the Transport Ingress module is extracted andfed into the optical signaling module (OSM). For example, assume thenetwork topology is such that the node A 900 receives the OSC first,then forwards it to node B 950. In this case, the extracted OSCwavelength from the OSM 920 is provided to the OSM 970. The incoming OSCwavelength from node A 900 is converted from optical to electrical andpacketized by the OSM 970, and the packets are sent to the Node Manager960 for proper signaling setup within the system. On the output side ofNode B 950, outgoing signaling messages are packetized and convertedinto an optical signal by OSM 970 and sent to the Transport Egressmodule for the next-hop OTS. Note that the OSC connection shown in FIG.9 is logical, and that the OSC typically propagates from TP card to TPcard where it is added to TP_(—)Eg by the outgoing OSM and extractedfrom TP_(—)In by the inbound OSM.

FIG. 9 shows the inter-operation of the Node Manager, LCMs, and the OSMin the OTS. The interconnection of the NMS 901 with the OTS/node 900 viarouters 904 and 906 is also shown. In particular, the node 900communicates with the NMS 901 via a POP gateway LAN 902, an NMS platform908 via an NMS LAN 909 and the routers 904 and 906. Thus, in addition tothe OSC, which enables the NMS to provide optical signals to each node,an electrical signaling channel enables a gateway node to communicatewith the NMS.

Each Node Manager at each OTS typically has three distinct networkinterfaces: 1) a 100 BaseT interface to the intra-OTS LAN, 2) a 100BaseT interface to remote NMS platforms, and 3) an out-of-band opticalsignaling channel (OSC) for node-to-node communications. OTSs that actas gateways to the NMS, such as node A 900, may use the 100 BaseTinterface, while non-gateways nodes, such as node B 950, need not havethis capability. Advantageously, the service provider's LAN is separatedfrom the OTS LAN for more efficient traffic handling. Layer 3 (L3) IProuting over the OSC provides nodes without gateway connectivity accessto nodes that have such Gateway capability. L3 here refers to the 3^(rd)layer of the OSI model, i.e., the network layer.

Moreover, there are three different levels of messaging-related softwareon the OTS Node Manager. First, an NMS connects to application softwareon the Node Manager through the Node Manager NMS agent. Second, an “S”(services) message interface provides an abstraction layer forconnecting Node Manager application software to a collection of CoreEmbedded Control software services, on the Node Manager, that serves toaggregate information sent to, or received from, the LCMs. Third, a “D”(driver) message interface connects the aggregating software of the NodeManager to the LCMs.

8. Optical Switch Fabric Module

FIG. 10 illustrates an optical switch fabric module architecture 210 inaccordance with the present invention. The OSF module 210 may bedesigned using 8×8 MEMS modules/chips 1010 as switching elements. Theswitching is done in the optical domain, and no O/E/O conversions areinvolved. All inputs to a switching element carry one wavelength (i.e.,one optical signal as opposed to a multiplex of optical signals), thusenabling wavelength level switching. Moreover, each optical output ofevery switching element goes through a variable optical attenuator (VOA)1050, which may be part of the switch fabric card, to equalize the poweracross all the wavelengths being subsequently multiplexed into onefiber. The switch fabric 210 is designed in a modular and scalablefashion so that it can be easily configured from a small-scale system toa large-scale system depending on the system configuration requirements.

The switch fabric 210 may receive optical inputs from an input module1070 such as a transport ingress card and/or an optical access ingresscard. The switch fabric provides the corresponding optical outputs todesignated ports of an output module 1080, such as a transport egresscard and/or an optical access egress card. Note that, for clarity ofdepiction in FIG. 10, only example light paths are shown.

In summary, the optical switch module provides wavelength-levelswitching, individually controllable signal attenuation of each output,interconnection to other modules via the optical fiber backplane, powerlevel control management for ensuring that the power of the signal thatis output between switches is acceptable, and path loss equalization forensuring that all channels have the same power. The optical switchmodule may also use an inherently very low cross-talk switch fabrictechnology such as MEMS, typically with a 2-D architecture, have amodular architecture for scalability with 8×8 switch modules, andprovide digital control of the MEMS fabric with electrostatic actuation.

9. Optical Transport Modules

The optical transport module (or “TP” module) is a multiplexedmulti-wavelength (per optical fiber) optical interface between OTSs inan optical network. For configuration and network management, thistransport module supports in-band control signals, which are within theEDFA window of amplification, e.g., 1525–1570 nm, as well as out-of-bandcontrol signals. For the out-of-band channel, the OTS may support a 1510nm channel interface. The OTS uses two primary types of transportmodules: Transport Ingress 240 (FIG. 11) and Transport Egress 245 (FIG.12).

In summary, the optical transport module provides demultiplexing of theOSC signal (ingress module), multiplexing of the OSC signal (egressmodule), optical amplification (ingress and egress modules) which mayuse low noise optical amplification and gain flattening techniques,demultiplexing of the multi-wavelength transport signal (ingressmodule), multiplexing of the individual wavelength signals (egressmodule). The optical transport module may also provide dynamicsuppression of optical power transients of the multi-wavelength signal.This suppression may be independent of the number of the survivingsignals (i.e., the signals at the transport ingress module that surviveat the transport egress module—some signals may be egressed due to dropmultiplexing), and independent of the number of the added signals (i.e.,the signals added at the transport egress module that are not present atthe transport ingress module—these signals may be added using addmultiplexing). The optical transport module may also provide dynamicpower equalization of individual signals, wavelength connection to theoptical switch fabric via the optical backplane, and pump control.

FIG. 11 shows the architecture for the Transport Ingress module 240. Themodule includes a demultiplexer 1105 to recover the OSC, an EDFApre-amplifier 1110, an EDFA power amplifier 1115, a demultiplexer 1120to demultiplex the eight wavelengths from the input port, and pumplasers 1122 and 1124 (e.g., operating at 980 nm).

Additionally, a filter 1107 filters the OSC before it is provided to theOSM. A coupler 1108 couples a tapped pre-amplified optical signal to theOPM, and to a PIN diode 1109 to provide a first feedback signal. Inparticular, the PIN diode outputs a current that represents the power ofthe optical signal. The OPM may measure the power of the optical signal(as well as other characteristics such as wavelength registration),typically with more accuracy than the PIN diode. The tap used allowsmonitoring of the multi-wavelength signal and may be a narrowbandcoupler with a low coupling ratio to avoid depleting too much signalpower out of the main transmission path. Similarly, a coupler 1126couples a tapped amplified optical signal to the OPM, and to a PIN diode1127 to provide a second feedback signal. Moreover, the pump laser 1122is responsive to a pump laser driver 1130 and a TEC driver 1132.Similarly, the high-power pump laser 1124 is responsive to a pump laserdriver 1140 and a TEC driver 1142. Both pump laser drivers 1130 and 1140are responsive to an optical transient and amplified spontaneousemission noise suppression function 1150, which in turn is responsive tothe feedback signals from the PIN diodes 1109 and 1127, and controlsignals from the LCM 1170. A DC conversion and filtering function may beused to provide local DC power.

The LCM 1170 provides circuit parameters and control by providingcontrol bits and receiving status bits, performs A/D and D/A dataconversions as required, and communicates with the associated NodeManager via an Ethernet or other LAN.

In particular, the LCM 1170 may provide control signals, e.g., for pumplaser current control, laser on/off, laser current remote control, TECon/off, and TEC remote current control. The LCM 1170 may receive statusdata regarding, e.g., pump laser current, backface photocurrent, pumplaser temperature, and TEC current.

FIG. 12 shows the architecture of the Transport Egress module 245, whichincludes a multiplexer 1205 to multiplex the eight wavelengths from theswitch fabric, an EDFA Pre-amplifier 1210, an EDFA Power amplifier 1215,a multiplexer 1220 to multiplex the eight wavelengths and the OSC, andpump lasers 1222 and 1224 (e.g., operating at 980 nm).

Analogous to the transport ingress module 240, the transport egressmodule 245 also includes a coupler 1208 that couples a tappedpre-amplified optical signal to the OPM module, and to a PIN diode 1209to provide a first feedback signal, e.g., of the optical signal power.Similarly, a coupler 1226 couples a tapped amplified optical signal tothe OPM module, and to a PIN diode 1227 to provide a second feedbacksignal. Moreover, the pump laser 1222 is responsive to a pump laserdriver 1230 and a TEC driver 1232. Similarly, the high-power pump laser1224 is responsive to a pump laser driver 1240 and a TEC driver 1242.Both pump laser drivers 1230 and 1240 are responsive to an opticaltransient and amplified spontaneous emission noise suppression function1250, which in turn is responsive to feedback signals from the PINdiodes 1209 and 1227, and the LCM 1270. A DC conversion and filteringfunction may be used to provide local DC power.

The LCM 1270 operates in a similar manner as discussed in connectionwith the LCM 1170 of the TP ingress module.

10. Optical Access Modules

The optical access module 230 provides an OTS with a single wavelengthinterface to access networks that use wavelengths that are compliantwith the optical network of the OTSs, such as ITU-grid compliantwavelengths. Therefore, third party existing or future ITU-gridwavelength compliant systems (e.g. GbE router, ATM switch, and FibreChannel equipment) can connect to the OTS. The optical access modulesare generally of two types: Optical Access Ingress 230 (FIG. 13) foringressing (inputting) one or more signals from an access network, andOptical Access Egress 235 (FIG. 14) for egressing (outputting) one ormore signals to an access network. The ITU grid specifies the minimumspacing and the actual wavelengths of the individual wavelengths in aWDM system.

Various functions and features provided by the optical access modulesinclude: optical amplification, connection to the optical switch fabricto route the signal for its wavelength provisioning, ITU-Grid wavelengthbased configuration, re-configuration at run-time, direct connectivityfor ITU-grid based wavelength signals, local wavelength switching, anddirect wavelength transport capability.

FIG. 13 shows the architecture of the Optical Access Ingress module 230,which includes EDFAs (EDFA-1, . . . ,EDFA-8) 1350, 2×1 switches 1310 and8×8 optical (e.g., MEMS) switch 1360.

In particular, each 2×1 switch receives a compliant wavelength (λ) fromthe faceplate and from the output of an ALI card via the opticalbackplane. In a particular example, eight compliant wavelengths from theoutputs of four ALI cards are received via the optical backplane. TheLCM 1370 provides a control signal to each switch to output one of thetwo optical inputs to an associated EDFA.

The LCM 1370 operates in a similar manner as discussed in connectionwith the TP ingress and egress modules.

Taps 1390 are provided for each of the signals input to the switch 1360to provide monitoring points to the OPM via the optical backplane.Similarly, taps 1395 are provided for each of the output signals fromthe switch 1360 to obtain additional monitoring points for the OPM viathe optical backplane.

In particular, the performance of the optical signals is monitored, anda loss of signal detected. Each wavelength passes through the opticaltap 1390 and a 1×2 optical splitter that provides outputs to: (a) a 8×1optical coupler to provide a signal to the OPM via the opticalbackplane, and (b) a PIN diode for loss of signal detection by the LCM1370. The OPM is used to measure the OSNR and for wavelengthregistration. The wavelengths at the taps 1395 are provided to a 8×1optical coupler to provide a signal to the OPM via the opticalbackplane. The optical taps, optical splitters and 8×1 optical couplerare passive devices.

FIG. 14 shows the architecture of the Optical Access Egress module 235.The module 235 includes EDFAs (EDFA-1, . . . ,EDFA-8) 1450, 1×2 switches1470 and 8×8 optical (e.g., MEMS) switch 1420.

In particular, the optical switch 1420 receives eight optical inputsfrom a switch fabric module 210. Taps 1410 and 1490 provide monitoringpoints for each of the inputs and outputs, respectively, of the switch1420 to the OPM via the optical backplane. The optical signals from theswitch fabric are monitored for performance and loss of signal detectionas discussed in connection with the Optical Access Ingress module 230.

The LCM 1472 provides control signals to the switches 1470 foroutputting eight compliant wavelengths to the faceplate, and eightcompliant wavelengths to the input of four ALI cards via the opticalbackplane. The LCM 1472 operates in a similar manner as discussedpreviously.

11. Access Line Interface Modules

This O/E/O convergent module is a multi-port single wavelength interfacebetween the switching system and legacy access networks usingnon-compliant wavelengths, e.g., around 1300 nm. The ALI module/card maybe provided as either a GbE interface module 220 a (FIG. 15) or SONETOC-n module. For example, FIG. 16 shows the ALI module configured as anOC-12 module 220 b, FIG. 17 shows the ALI module configured as an OC-48module 220 c, and FIG. 18 shows the ALI module configured as an OC-192module 220 d. Other OC-n speeds may also be supported. In FIGS. 15–18,the solid lines denote transport data flow, and the dashed lines denotecontrol data flow.

Referring to FIG. 15, the GbE module 220 a provides dual data paths,each of which accepts four GbE signals, and multiplexes them to a singleOC-48 signal. In the other direction, the module accepts an OC-48 signaland demultiplexes it into four GbE signals in each of the two paths.

The GbE module 220 a includes SONET framers 1510 and 1520 that handleaggregation and grooming from each GbE port. The SONET framers may usethe Model S4083 or Yukon chips from Advanced Micro Circuits Corporation(AMCC) of Andover, Mass. The module 220 a aggregates two or more GbElines into each SONET framer 1510, 1520, which support OC-48 and OC-192data rates. The module 220 a also performs wavelength conversion to oneof the ITU-grid wavelengths. For each of the modules 220 a–220 d, thedesired ITU-grid wavelength is configured at initial path signalingsetup.

For scheduling the use of OA bandwidth to support multiple legacy accessnetworks, a variety of scheduling algorithms may be used when theaggregate bandwidth of the ALI inputs is greater than that of the ALIoutput. Such algorithms are typically performed by FPGAs 1540 and 1542.For example, one may use round robin scheduling, where the samebandwidth is allocated to each of the GbE interfaces, or weighted roundrobin scheduling, where relatively more bandwidth is allocated tospecified GbE interfaces that have a higher priority.

The MAC/PHY chips 1530, 1532, 1534, 1536 communicate with GbEtransceivers, shown collectively at 1525, which in turn provide O-E andE-O conversion. MAC, or Media Access Control, refers to processing thatis related to how the medium (the optical fiber) is accessed. The MACprocessing performed by the chips may include frame formatting, tokenhandling, addressing, CRC calculations, and error recovery mechanisms.The Physical Layer Protocol, or PHY, processing, may include dataencoding or decoding procedures, clocking requirements, framing, andother functions. The chips may be AMCC's Model S2060. The module 220 aalso includes FPGAs 1540, 1542 which are involved in signal processing,as well as a control FPGA 1544. The FPGAs 1540, 1542 may be the ModelXCV300 from Xilinx Corp., San Jose, Calif. Optical transceivers (TRx)1550 and 1552 perform O-E and E-O conversions. In an ingress mode, whereoptical signals from an access network are ingressed into an OTS via thean ALI card, the MAC/PHY chips 1530–1536 receive input signals from theGbE transceivers 1525, and provide them to the associated FPGA 1540 or1542, which in turn provides the data in an appropriate format for theSONET framers 1510 and 1520, respectively. The SONET framers 1510 or1520 output SONET-compliant signals to the transceivers 1550 and 1552,respectively, for subsequent E-O conversion and communication to theOA_(—)In cards 230 via the optical backplane.

In an egress mode, where optical signals are egressed from the alloptical network to an access network via the OTS, SONET optical signalsare received from the optical access egress cards 235 at thetransceivers 1550 and 1552, where O-E conversion is performed, theresults of which are provided to the SONET framers 1510 or 1520 forde-framing. The de-framed data is provided to the FPGAs 1540 and 1542,which provide the data in an appropriate format for the MAC/PHY chips1530–1536. The MAC/PHY chips include FIFOs for storing the data prior toforwarding it to the GbE transceivers 1525.

The control FPGA 1544 communicates with the ALI card's associated LCM,and also provides control signals to the transceivers 1550 and 1552,FPGAs 1540 and 1542, SONET framers 1510 and 1520, and MAC/PHY chips1530–1536. The FPGA 1544 may be the Model XCV150 from Xilinx Corp.

In summary, the ALI modules may include module types 220 a–220 c,having: 16 physical ports (8 input and 8 output) of GbE, OC-12, orOC-48, and four physical ports (two input and two output) of OC-192.Module 220 d has four physical ports on either end. The ALI modules maysupport OC-12 to OC-192 bandwidths (or faster, e.g., OC-768), providewavelength conversion, e.g., from the 1250–1600 nm range, toITU-compliant grid, support shaping and re-timing through O-E-Oconversion, provide optical signal generation and amplification, and mayuse a wavelength channel sharing technique.

See FIG. 28 for additional related information.

FIGS. 16, 17 and 18 show the architecture of the OC-12, OC-48, andOC-192 access line interface cards, respectively. See also FIG. 29 foradditional related information.

FIG. 16 shows an OC-12 module 220 b, which aggregates four or more OC-12lines into each SONET framer 1610 or 1620, which support OC-48 datarates.

In an optical ingress mode, Quad PHY functions 1630 and 1640 eachreceive four signals from OC-12 interfaces via transceivers, showncollectively at 1625, and provide them to corresponding SONET framers1610 and 1620, respectively. The SONET Framers may use AMCC's ModelS4082 or Missouri chips. The Quad PHY functions may each include four ofAMCC's Model S3024 chips. The SONET framers 1610 and 1620 provide thedata in frames. Since four OC-12 signals are combined, a speed of OC-48is achieved. The framed data is then provided to optical transceivers1650 and 1652 for E-O conversion, and communication to the opticalaccess ingress cards 230 via the optical backplane. The SONET framers1610 and 1620 may also communicate with adjacent ALI cards via anelectrical backplane to receive additional input signals, e.g., toprovide a capability for switch protection mechanisms. The electricalbackplane may comprise a parallel bus that allows ALI cards in adjacentbays to communicate with one another. The electrical backplane may alsohave a component that provides power to each of the cards in the OTSbay.

In an optical egress mode, optical signals are received by thetransceivers 1650 and 1652 from the OA_(—)Eg cards and provided to theSONET framers 1610 and 1620 following O-E conversion. The SONET framers1610 and 1620 provide the signals in a format that is appropriate forthe Quad PHY chips 1630 and 1640.

The control FPGA 1644 communicates with the ALI card's associated LCM,and also provides control signals to the transceivers 1650 and 1652,SONET framers 1610 and 1620, and Quad PHY chips 1630 and 1640.

FIG. 17 shows an OC-48 module 220 c, which aggregates two or more OC-48lines into each SONET framer 1710 and 1720, which support OC-192 datarates.

In an optical ingress mode, PHY chips 1730, 1732, 1734 and 1736 eachreceive two signals from OC-48 interfaces via transceivers 1725 andprovide them to corresponding SONET framers 1710 and 1720, respectively.The SONET framers 1710 and 1720 provide the signals in frames. Sincefour OC-48 signals are combined, a speed of OC-192 is achieved. Thesignals are then provided to optical transceivers 1750 and 1752 for E-Oconversion, and for communication to optical access ingress cards 230via the optical backplane. The SONET framers 1710 and 1720 may alsocommunicate with adjacent ALI cards.

In an optical egress mode, optical signals are received by the opticaltransceivers 1750 and 1752 from optical access egress cards and providedto the SONET framers 1710 and 1720 following O-E conversion at thetransceivers 1650, 1652. The SONET framers 1710 and 1720 provide thesignals in a format that is appropriate for the OC-48 interfaces. Theformatted optical signals are provided to the OC-48 interfaces via thePHY chips 1730–1736. Moreover, dedicated ports may be provided, whichobviate MAC processing.

The FPGA 1744 communicates with the ALI card's associated LCM, and alsoprovides control signals to the transceivers 1750 and 1752, SONETframers 1710 and 1720, and PHY chips 1730–1736.

FIG. 18 shows an OC-192 module 220 d, which provides one OC-192 lineinto each SONET framer 1810, 1820, which support OC-192 data rates.

In an optical ingress mode, PHY chips 1830 and 1832 each receive asignal from OC-192 interfaces via transceivers 1825 and provide it tocorresponding SONET framers 1810 and 1820, respectively, which providethe signals in frames. The signals are then provided to opticaltransceivers 1850 and 1852 for E-O conversion, and communicated toOA_(—)In cards 230 via the optical backplane. The SONET framers 1810 and1820 may also communicate with adjacent ALI cards.

In an optical egress mode, optical signals are received by the opticaltransceivers 1850 and 1852 from the OA Eg cards and provided to theSONET framers 1810 and 1820 following O-E conversion. The SONET framers1810 and 1820 provide the signals in a format that is appropriate forthe OC-192 interfaces. The formatted signals are provided to the OC-192interfaces via the PHY chips 1830 and 1832.

The FPGA 1844 communicates with the ALI card's associated LCM, and alsoprovides control signals to the transceivers 1850 and 1852, SONETframers 1810 and 1820, and PHY chips 1830 and 1832.

12. Optical Performance Monitoring Module

Referring to FIG. 19, the Optical Performance Monitoring (OPM) module260 is used for several activities. For example, it monitors the powerlevel of a multi-wavelength signal, the power level of a singlewavelength signal, and the optical signal-to-noise ratio (OSNR) of eachwavelength. It also measures wavelength registration. Each incomingwavelength power variation should be less than 5 dB and each out-goingwavelength power variation should be less than 1 dB.

In particular, the OPM acts as an optical spectrum analyzer. The OPM maysample customer traffic and determine whether the expected signalslevels are present. Moreover, the OPM monitoring is in addition to theLCM monitoring of a line card, and generally provides higher resolutionreadings. The OPM is connected through the optical backplane, e.g.,using optical fibers, to strategic monitoring points on the line cards.The OPM switches from point to point to sample and take measurements.Splitters, couplers and other appropriate hardware are used to accessthe optical signals on the line cards.

The OPM module and signal processing unit 260 communicates with a LCM1920, and receives monitoring data from all the line card monitoringpoints from a 1×N optical switch 1930 via the optical backplane of theOTS. A faceplate optical jumper 1912 allows the OPM module and signalprocessing unit 260 and the optical switch 1930 to communicate. Aconversion and filtering function may be used to provide local DC power.

The LCM 1920 (like all other LCMs of a node) communicates with the NodeManager via the intra-node LAN.

In summary, the OPM supports protection switching, fault isolation, andbundling, and measures optical power, OSNR of all wavelengths (bysweeping), and wavelength registration. Moreover, the OPM, whichpreferably has a high sensitivity and large dynamic range, may monitoreach wavelength, collect data relevant to optical devices on thedifferent line cards, and communicate with the NMS (via the LCM and NodeManager). The OPM is preferably built with a small form factor.

13. OTS Chassis Configurations

The OTS is designed to be flexible, particularly as a result of itsmodular system design that facilitates expandability. The OTS is basedon a distributed architecture where each line card has an embeddedcontroller. The embedded controller performs the initial configuration,boots up the line card, and is capable of reconfiguring each line cardwithout any performance impact on the whole system.

FIG. 20 illustrates a physical architecture of an OTS chassis or bay(receiving apparatus) in an OXC configuration 2000 in accordance withthe present invention. There may be two OTS Node Manager circuit packsin each OTS node, namely a primary and a backup. Each of these circuitpacks corresponds to Node Manager 250 of FIG. 2. In the exampleconfiguration of FIG. 20, a total of twenty-two circuit packs/line cardsare provided in receiving locations or slots of the bay, with two ofthose twenty-two circuit packs being OTS Node Manager cards. An OTS istypically designed to provide a certain number of slots per shelf in itsbay. Based upon the number of shelves, provision is made for up to acertain number of total circuit packs for the bay, such as, for example,twenty-four circuit packs in a bay, to allow for differentconfigurations of OTS to be constructed. Communication to or from thebay is via the OTS Node Manager.

FIG. 21 shows a fully configured OTS 2100 in a OXC/OADM configuration.FIG. 22 shows a fully configured ALI card bay 2200.

Optical cables in an OTS are typically connected through the opticalbackplane to provide a simple and comprehensive optical cableconnectivity of all of the optical modules. In addition to providing forthe LAN, the electrical backplane handles power distribution, physicalboard connection, and supports all physical realizations with full NEBSlevel 3 compliance. Note that since “hot” plugging of cards into an OTSis often desirable, it may be necessary to equip such cards withtransient suppression on their power supply inputs to prevent thepropagation of powering-up transients on the electrical backplane'spower distribution lines.

In one approach to managing the complexity of the optical backplane,locations or slots in the OTS bay may be reserved for specific types ofline cards since the required optical coupling of a line card depends onits function, and it is desirable to minimize the complexity of theoptical fiber connections in the optical backplane.

Each of the optical circuit cards also has a connection to an electricalbackplane that forms the LAN for LCM-Node Manager communications. Thisconnection is uniform for each card and may use an RJ-45 connector,which is an 8-wire connector used on network interface cards.

The OTS is flexible in that it can accommodate a mix of cards, includingOptical Access and Transport line cards. Thus, largely generic equipmentcan be provided at various nodes in a network and then a particularnetwork configuration can be remotely configured as the specific needarises. This simplifies network maintenance and provides greatflexibility in reconfiguring the network. For example, the OTS mayoperate as a pure transport optical switch if it is configured with allcards are transport cards (FIG. 20), e.g., eight transport ingress(TP_(—)In) cards and eight transport egress cards (TP_(—)Eg). Moreover,each TP_(—)In card has one input port/fiber and each TP_(—)Eg card hasone output port/fiber. In a particular implementation, each port/fibersupports eight wavelength-division multiplexed λ's, along with the OSC.

The OTS may operate as an Add/Drop terminal if it is configured withALI, OA, and TP cards (FIGS. 21 and 22). A wide range of configurationsis possible depending on the mix of compliant and non-compliantwavelengths supported. For example, a typical configuration mightinclude sixteen ALI cards for conversion of non-compliant wavelengths,four OA_(—)In cards, four OA_(—)Eg cards, four TP_(—)In cards, and fourTP_(—)Eg cards. Note that since the ALI cards provide wavelengthconversion in this embodiment, no wavelength conversion need beperformed within the optical fabric. However, wavelength conversionwithin the optical fabric is also a possibility as the switch fabrictechnology develops.

Moreover, the OTS is scalable since line cards may be added to the spareslots in the bay at a later time, e.g., when bandwidth requirements ofthe network increase. Furthermore, multiple OTS bays can be connectedtogether to further expand the bandwidth-handling capabilities of thenode and/or to connect bays having different types of line cards. Thisconnection may be realized using a connection like the ALI card-to-OAcard connection via the optical backplane.

Having now discussed the different types of modules/line cards and theOTS chassis configurations, some features of the OTS when configured asa OXC or OADM are summarized in Table 2 in terms of Access LineInterface, Transport/Switching, and Management functions. Since the OADMcan be equipped with transport cards (TP_(—)In and TP_(—)Eg), itperforms all of the functions listed, while the dedicated OXCconfiguration performs the switching/transport and management functions,but not the ALI functions.

For example, the Node Manager or NMS may control the OTS to configure itin the OXC or OADM modes, or to set up routing for light paths in thenetwork.

TABLE 2 Product Feature OADM OXC Access Line Interface Adding/droppingof wavelengths X Grooming of optical signals X Non-ITU-compliantwavelength conversion X Optical Signal Generation/Modulation(Timing/Shaping) X Switching/Transport Multiplexing and demultiplexingof multi-wavelength X X signals into individual wavelengthsCross-connection of the individual wavelengths X X Amplification ofoptical signals X X Protection switching of wavelengths X X Dynamicpower equalization of the optical signals X X Dynamic suppression ofoptical power transients of the X X multi-wavelength signal ManagementPerformance monitoring of wavelengths X X Operations and maintenancecapabilities to support TMN X X

14. System Configurations

In an important aspect of the invention, each OTS can be used in adifferent configuration based on its position within an optical network.In the optical cross-connect (OXC) configuration, the input transportmodule, the switch fabric and the output transport module are used. FIG.23 shows the modules used for the OXC configuration. In particular, theOTS 200 a includes the TP_(—)In modules 240 and the TP_(—)Eg modules245. Each TP_(—)In card may receive one fiber that includes, e.g., eightmultiplexed data channels and the OSC. Similarly, each TP_(—)Eg cardoutputs eight data channels in a multiplex and the OSC on an associatedfiber.

FIG. 24 shows the modules used for the OADM configuration when theincoming optical signals are compliant, e.g., with the ITU grid. In thiscase, the access line modules are not needed since the wavelengths areinput directly from the access network to the OA_(—)In cards. Here, theOTS 200 b includes the TP_(—)In modules 240, the TP_(—)Eg modules 245,the OA_(—)In modules 230, and the OA_(—)Eg modules 235. Note that theOA_(—)In and OA_(—)Eg cards are typically provided in pairs to providebi-directional signaling.

FIGS. 25 and 26 show the OTS configurations when non-compliantwavelengths are used. The non-compliant wavelengths may include, e.g.,eight OC-12 wavelengths and eight OC-48 wavelengths. In FIG. 25, in anadd only multiplexing configuration, the OTS 200 c uses the ALI modules220 for converting the non-compliant wavelengths to compliantwavelengths, e.g., using any known wavelength conversion technique. TheOA_(—)In modules 230 receive the compliant wavelengths from the ALIs 220and provide them to the switch fabric 210. The switched signals are thenprovided to the TP_(—)Eg modules 245 for transport on optical fibers inthe optical network. Note that, typically, bidirectional signaling isprovided to/from the access network via the ALI cards. Thus, theprocesses of FIGS. 25 and 26 may occur at the same time via one or moreALI cards.

In FIG. 26, in a drop-only multiplexing configuration, the OTS 200 dincludes the TP_(—)In module 240 for receiving the optical signal viathe optical network, the OA Eg modules 235 for receiving the opticalsignals from the switch 210, and the ALI modules 220 for converting thecompliant wavelengths to non-compliant wavelengths for use by the accessnetwork. The non-compliant wavelengths may be provided as, e.g., eightOC-12 wavelengths and eight OC-48 wavelengths.

For concurrent add and drop multiplexing of non-compliant signals, theALI modules both provide inputs to the OA_(—)In modules 230, and receiveoutputs from the OA_(—)Eg modules 245.

Similarly, any concurrent combination of the following is possible: (a)inputting OTS-compliant signals from one or more access networks to theOA_(—)In modules, (b) inputting non-OTS-compliant signals from one ormore access networks to the ALI modules, (c) outputting signals, whichare both OTS— and access-network compliant, from the OA_(—)Eg modules toone or more access networks, and (d) outputting signals, which areOTS-compliant but non-compliant with an access network, to the ALImodules.

15. Transparent Data Transfer

A primary service enabled by the present invention is a transparentcircuit-switched light path. Compared to conventional services, theseflows are distinguished by a large quantity of bandwidth provided, and asetup time measured in seconds.

FIG. 27 shows a simple example of wavelength adding, dropping, andcross-connection. Generally, in an example network 2700, light paths areterminated at the OADMs 2710, 2730, 2750 and 2760 (at edge nodes of thenetwork 2700), and switched through the OXCs 2720 and 2740 (at internalnodes of the network 2700). When no wavelength conversion is performedin the OXCs, the same wavelength carrying the light path is used on alllinks comprising the light path, but the wavelength can be reused ondifferent links. For example, λ1 can be used in light paths 2770 and2780, λ2 can be used in light path 2775, and λ3 can be used in lightpaths 2785 and 2790.

From a user perspective, this transparent data transfer service isequivalent to a dedicated line for SONET services, and nearly equivalentto a dedicated line for GbE services. Since the OTS operation isindependent of data rate and protocol, it does not offer a Quality ofService in terms of bit error rate or delay. However, the OTS maymonitor optical signal levels to ensure that the optical path signal hasnot degraded. Also, the OTS may perform dynamic power equalization ofthe optical signals, and dynamic suppression of optical power transientsof the multi-wavelength signal independently of the number of thesurviving signals, and independently of the number of the added signals.The OTS may thus measure an Optical Quality of Service (OQoS) based onoptical signal-to-noise ratio (OSNR), and wavelength registration.

Table 3 provides a summary of transparent data transfer functionsperformed by the OTS for each type of interface. The simplest case isthe receipt of a compliant OC-12/48 signal by the Optical Access module.

TABLE 3 Line Interface Functions Compliant Optical (SONET) ChannelMultiplexing/Demultiplexing Signal AmplificationSwitching/Cross-Connection GbE Packet Multiplexing/DemultiplexingAggregation/Grooming SONET Framing Modulation/Demodulation O-EConversion on input E-O Conversion on output ChannelMultiplexing/Demultiplexing Signal AmplificationSwitching/Cross-Connection Non-compliant Optical O-E-O translation fromnon-compliant Waveforms wavelength (e.g., 1310 nm) Aggregation/GroomingRetiming/Reshaping Channel Multiplexing/Demultiplexing SignalAmplification Switching/Cross-Connection

The signal shaping and timing may be performed on the ALI cards usingon-off keying with Non-Return-to-Zero signaling.

In one possible embodiment, eight compliant waveforms are supportedbased on the ITU-specified grid, with 200 Ghz or 1.6 nm spacing, shownin Table 4. These are eight wavelengths from the ITU grid.

TABLE 4 Wavelength # Wavelength registration 1 1549.318 nm 2 1550.921 nm3 1552.527 nm 4 1554.137 nm 5 1555.750 nm 6 1557.366 nm 7 1558.986 nm 81560.609 nm

For compliant wavelengths received on the OA modules, the receivedsignal is optically amplified and switched to the destination.

For non-compliant wavelengths, signals are converted to electrical formand are groomed. If the current assignment has several lower rate SONETinput streams, e.g., OC-12, going to the same destination, the ALI cangroom them into one higher rate stream, e.g., OC-48. After beingswitched to the destination port, the stream is multiplexed by a TPmodule onto a fiber with other wavelengths for transmission. Moreover,for non-compliant wavelengths, the OTS performs a wavelength conversionto an ITU wavelength, and the stream is then handled as a compliantstream. Conversion of optical signals from legacy networks toITU-compliant wavelengths listed in Table 4 may be supported.

FIG. 28 illustrates Gigabit Ethernet networks accessing a managedoptical network in accordance with the present invention.

The GbE interface supports the fiber media GbE option, where the mediaaccess control and multiplexing are implemented in the electricaldomain. Therefore, the flow is somewhat different from SONET. The GbEpacketized data streams are received as Ethernet packets, multiplexedinto a SONET frame, modulated (initial timing and shaping), andconverted to a compliant wavelength. After the compliant wavelengths areformed, they are handled as compliant wavelength streams as describedabove.

The following example clarifies how Ethernet packets are handled. GbE12802, GbE2 2804, GbE3 2806, GbE4 2808, GbE5 2840, GbE6 2842, GbE7 2844and GbE8 2846 are separate LANs. Typically, each of the active ports aregoing to a different destination, so dedicated wavelengths are assigned.If two or more GbE ports have the same destination switch, they may bemultiplexed onto the same wavelength. In this example, each of four GbEports are transmitted to the same destination (i.e., OADM B 2830) but toseparate GbE LANs (GbE1 is transmitted to GbE5, GbE2 is transmitted toGbE6, etc.). The client can attach as many devices to the GbE asdesired, but their packets are all routed to the same destination.

In this case, the processing flow proceeds as follows. First, the OADM A2810 receives GbE packets on GbE1 2802, GbE2 2804, GbE3 2806, and GbE42808. The OADM A 2810 performs O-E conversion and multiplexes thepackets into SONET frames at the ALI/OA function 2812. OADM A 2810performs the E-O conversion at the assigned λ, also at the ALI/OAfunction 2812. The resulting optical signal is switched through theswitch fabric (SW) 2814 to the transport module (egress portion) 2816,and enters the network 2820. The optical signal is switched through theoptical network 2820 to the destination switch at OADM B 2830. At theOADM B 2830, the optical signal is received at the transport module(ingress portion) 2832, and switched through the switch fabric 2834 tothe OA_(—)Eg/ALI function 2836. The OADM B 2830 extracts the GbE packetsfrom the SONET frame at the OA/ALI function 2836. Finally, the OADM B2830 demultiplexes the packets in hardware at the OA/ALI function 2836to determine the destination GbE port and transmits the packet on thatport.

Since the ALI 2812 in the OADM A 2810 may receive packets on differentports at the same time, the ALI buffers one of the packets fortransmission after the other. However, appropriate hardware can beselected for the ALI such that the queuing delays incurred arenegligible and the performance appears to be like a dedicated line.

Note that, in this example, all GbE ports are connected to the same ALI.However, by bridging the Ethernets, the service provider can configurethe traffic routing within the GbE networks to ensure that traffic goingto the same destination is routed to the same input GbE port on theoptical switch. Multiplexing GbE networks attached to different ALIs isalso possible.

Refer also to FIG. 15 and the related discussion.

The QoS in terms of traditional measures is not directly relevant to theoptical network. Instead, the client (network operator) may controlthese performance metrics. For example, if the client expects that theGbE ports will have a relatively modest utilization, the client maychoose to assign four ports to a single OC-48 λ operating at 2.4 Gbps(assuming they all have the same destination port). In the worst case,the λ channel may be oversubscribed, but for the most part, itsperformance should be acceptable.

However, some QoS features can be provided on the GbE ALI cards. Forexample, instead of giving all of GbE streams equal priority using roundrobin scheduling, weighted fair queuing may be used that allows theclient to specify the weights given to each stream. In this way, theclient can control the relative fraction of bandwidth allocated to eachstream.

Similarly, for ATM, the client may be operating a mix of CBR, VBR, ABR,and UBR services as inputs to the OADM module. However, the switchingsystem does not distinguish the different cell types. It simply forwardsthe ATM cells as they are received, and outputs them on the port asdesignated during setup.

FIG. 29 shows an example of interconnectivity of the optical networkwith OC-12 legacy networks. Other OC-n networks may be handledsimilarly. Refer also to FIGS. 16–18 and the related discussions. Theexample shows four OC-12 networks 2902, 2904, 2906 and 2908, connectedto the optical network 2920 through the OC-12 ALI card 2912. Similarly,four OC-12 networks 2940, 2942, 2944 and 2946 are connected to the OC-12ALI card 2936 at the OADM B 2930.

In the example, the processing flow proceeds as follows. First, the OADMA 2910 receives packets on OC-12 1 (2902), OC-12 2 (2904), OC-12 3(2906), and OC-12 4 (2908). The OADM A 2910 multiplexes the packets intoSONET frames at OC-48 at the ALI/OA module 2912 using TDM. For compliantwavelengths, OC-n uses only the OA portion, not the ALI portion. Fornon-compliant wavelengths, the ALI is used for wavelength conversion,through an O-E-O process, then the OA is used for handling thenewly-compliant signals. The resulting optical signal is switchedthrough the switch fabric (SW) 2914 to the transport module (egressportion) (TP) 2916, and enters the network 2920. The optical signal isswitched through the optical network 2920 to the destination switch atOADM B 2930. At the OADM B 2930, the optical signal is received at thetransport module (ingress portion) 2932, and switched through the switchfabric (SW) 2934 to the OA/ALI function 2936. The OADM B 2930 extractsthe packets from the SONET frame at the OA/ALI function 2936. The OADM B2930 demultiplexes the packet in hardware at the OA/ALI function 2936 todetermine the destination port, and transmits the packet on that port.

16. Routing and Wavelength Assignment

The routing block 3120 of FIG. 31 refers to a Routing and WavelengthAssignment (RWA) function that may be provided as software running onthe NMS for selecting a path in the optical network between endpoints,and assigning the associated wavelengths for the path. Forimplementations where the OTS does not provide wavelength conversion,the same wavelength is used on each link in the path, i.e., there iswavelength continuity on each link.

A “Light Wave OSPF” approach to RWA, which is an adaptive source basedapproach based on the Open Shortest Path First (OSPF) routing asenhanced for circuit-switched optical networks, may be used. Developedoriginally for (electrical) packet networks, OSPF is a link statealgorithm that uses link state advertisement (LSA) messages todistribute the state of each link throughout the network. Knowing thestate of each link in the network, each node can compute the best path,e.g., based on OSPF criteria, to any other node. The source node, whichmay be the Node Manager associated with the path tail, computes the pathbased on the OSPF information.

OSPF is particularly suitable for RWA since it is available at low risk,e.g., easily extended to support traffic engineering and wavelengthassignment, scalable, e.g., able to support large networks using one ortwo levels of hierarchies, less complex than other candidate techniques,and widely commercially accepted.

Several organizations have investigated the enhancement of OSPF tosupport optical networks and several alternative approaches have beenformulated. The major variation among these approaches involves theinformation that should be distributed in the LSA messages. As aminimum, it is necessary to distribute the total number of activewavelengths on each link, the number of allocated wavelengths, thenumber of pre-emptable wavelengths, and the risk groups throughout thenetworks. In addition, information may be distributed on the associationof fibers and wavelengths such that nodes can derive wavelengthavailability. In this way, wavelength assignments may be madeintelligently as part of the routing process. The overhead incurred canbe controlled by “re-advertising” only when significant changes occur,where the threshold for identifying significant changes is a tunableparameter.

Furthermore, the optical network may support some special requirements.For example, in the ODSI Signaling Control Specification, the client mayrequest paths that are disjoint from a set of specified paths. In theCreate Request, the client provides a list of circuit identifiers andrequest that the new path be disjoint from the path of each of thesepaths. When the source node determines the new path, the routingalgorithm must specifically exclude the links/switches comprising thesepaths in setting up the new path.

It is expected that the light paths will be setup and remain active foran extended period of time. As a result, the incremental assignment ofwavelengths may result in some inefficiency. Therefore, it may improveperformance to do periodic re-assignments.

17. Flash Memory Architecture

Flash memory is used on all controllers for persistent storage. Inparticular, the Node Manager flash memory may have 164 Mbytes while LCMflash memories may have 16 Mbytes. The Intel 28F128J3A flash chip,containing 16 Mbytes, may be used as a building block. Designing flashmemory into both controllers obviates the need for ROM on bothcontrollers. Both controllers boot from their flash memory. Shouldeither controller outgrow its flash storage, the driver can be modifiedto apply compression techniques to avoid hardware modifications.

The flash memory on all controllers may be divided into fixed partitionsfor performance. The Node Manager may have five partitions, including(1) current version Node Manager software, (2) previous version(rollback) Node Manager software, (3) LCM software, (4) Core Embeddedsoftware data storage, and (5) application software/data storage.

The LCM may have 3 partitions, including (1) LCM software, (2) previousversion (rollback) LCM software, and (3) Core Embedded software datastorage.

The flash memory on both the Node Manager and LCM may use a specialdevice driver for read and write access since the flash memory hasaccess controls to prevent accidental erasure or reprogramming.

For write access, the flash driver requires a partition ID, a pointer tothe data, and a byte count. The driver first checks that the size of thepartition is greater than or equal to the size of the read buffer, andreturns a negative integer value if the partition is too small to holdthe data in the buffer. The driver then checks that the specifiedpartition is valid and, if the partition is not valid, returns adifferent negative integer. The driver then writes a header containing atimestamp, checksum, and user data byte count into the named partition.The driver then writes the specified number of bytes starting from thegiven pointer into the named partition. The flash driver returns apositive integer value indicating the number of user data bytes writtento the partition. If the operation fails, the driver returns a negativeinteger value indicating the reason for failure (e.g., device failure).

For read access, the flash driver requires a partition ID, a pointer toa read data buffer, and the size of the data buffer. The driver checksthat the size of the read buffer is greater than or equal to the size ofthe data stored in the partition (size field is zero if nothing has beenstored there). The driver returns a negative integer value if the bufferis too small to hold the data in the partition. The driver then does achecksum validation of the flash contents. If checksum validation fails,the driver returns a different negative integer. If the checksumvalidation is successful, the driver copies the partition contents intothe provided buffer and return a positive integer value indicating thenumber of bytes read. If the operation fails, the driver returns anegative integer value indicating the reason for failure (e.g., devicefailure).

18. Hierarchical Optical Network Structure

The all-optical network architecture is based on an open, hierarchicalstructure to provide interoperability with other systems and accommodatea large number of client systems.

FIG. 30 depicts the hierarchical structure of the all-optical networkarchitecture for a simple case with three networks, network A 3010,network B 3040 and network C 3070. Typically, a network is managed by athree-tiered control architecture: i) at the highest level a leaf NMSmanages the multiple OTSs of its network, ii) at the middle level eachOTS is managed individually by its associated Node Manager, and iii) atthe lowest level each line card of a node (except the Node Manager) ismanaged by an associated Line Card Manager.

The nodes, such as nodes 3012, 3014, 3042 and 3072 depict the opticalswitching hardware (the OTSs). Moreover, network A 3010 and network B3040 communicate with one another via OTSs 3012 and 3042, and network A3010 and network C 3040 communicate with one another via OTSs 3014 and3072. In this example, each network has its own NMS. For example,network A 3010 has an NMS 3015, network B 3040 has an NMS 3045, andnetwork C 3070 has an NMS 3075.

When multiple NMSs are present, one is selected as a master or root NMS.For example, the NMS 3015 for Network A 3010 may be the root NMS, suchthat the NMSs 3045 and 3075 for Networks B and C, respectively, aresubservient to it.

Each NMS includes software that runs separate and apart from the networkit controls, as well as NMS agent software that runs on each NodeManager of the NMS's network. The NMS agent software allows the each NMSto communicate with the Node Managers of each of its network's nodes.

Moreover, each NMS may use a database server to store persistent data,e.g., longer-life data such as configuration and connection information.The database server may use LDAP, and Oracle® database software to storelonger-life data such as configuration and connection information.

LDAP is an open industry standard solution that makes use of TCP/IP,thus enabling wide deployment. Additionally, a LDAP server can beaccessed using a web-based client, which is built into many browsers,including the Microsoft Explorer® and Netscape Navigator® browsers. Thedata can be stored in a separate database for each instance of anetwork, or multiple networks can share a common database serverdepending on the size of the network or networks. As an example,separate databases can be provided for each of networks A, B and C,where each database contains information for the associated network,such as connection, configuration, fault, and performance information.In addition, the root NMS (e.g., NMS 3015) can be provided with asummary view of the status and performance data for Networks B and C.

The hierarchical NMS structure is incorporated into the controlarchitecture as needed.

19. System Functional Architecture

The functionality provided by the OTS and NMS, as well as the externalnetwork interfaces are shown in FIG. 31. As indicated by the legend3102, the path restoration 3115 and network management 3105functionalities are implemented in the NMS, while the routing 3120,signaling 3135 including user-network signaling 3136 and internalsignaling 3137 (internal to the network), agent/proxy 3110, andprotection 3145 are real-time functionalities implemented in the NodeManager.

External interfaces to the optical network system include: (1) a clientsystem 3140 requesting services, such as a light path, from the opticalnetwork via the UNI protocol, (2) a service provider/carrier NMS 3130used for the exchange of management information, and (3) a hardwareinterface 3150 for transfer of data. An interface to a local GUI 3125 isalso provided.

The client system 3140 may be resident on the service provider'shardware. However, if the service provider does not support UNI, thenmanual (e.g., voice or email) requests can be supported. Light path(i.e., optical circuit) setup may be provided, e.g., using a signaledlight path, a provisioned light path, and proxy signaling. Inparticular, a signaled light path is analogous to an ATM switchedvirtual circuit, such that a service provider acts as UNI requestor andsends a “create” message to initiate service, and the Optical NetworkController (ONC) invokes NNI signaling to create a switched lightpath. Aprovisioned lightpath is analogous to an ATM permanent virtual circuit(PVC), such that a service provider via the NMS requests a lightpath becreated (where UNI signaling is not used), and the NMS commands theswitches directly to establish a lightpath. The NMS can also use theservices of a proxy signaling agent to signal for the establishment of alightpath.

The service provider/carrier NMS interface 3130 enables the serviceprovider operator to have an integrated view of the network using asingle display. This interface, which may be defined using CORBA, forinstance, may also be used for other management functions, such as faultisolation.

The local GUI interface 3125 allows local management of the opticalnetwork by providing a local administrator/network operator with acomplete on-screen view of topology, performance, connection, fault andconfiguration management capabilities and status for the opticalnetwork.

The control plane protocol interface between the service providercontrol plane and the optical network control plane may be based on an“overlay model” (not to be confused with an overlay network used by theNMS to interface with the nodes), where the optical paths are viewed bythe service provider system as fibers between service provider systemendpoints. In this model, all of the complexities of the optical networkare hidden from the user devices. Thus, the routing algorithm employedby the optical network is separate from the routing algorithms employedby the higher layer user network. The internal optical network routingalgorithm, internal signaling protocols, protection algorithms, andmanagement protocols are discussed in further detail below. Theall-optical network based on the OTS may be modified from the “overlaymodel” architecture to the “peer model” architecture, where the userdevice is aware of the optical network routing algorithm and the userlevel. The optical network and user network routing algorithms areintegrated in the “peer model” architecture.

20. Internal Network Signaling

20.1 Protocol Description

The Internal Signaling function 3137 of FIG. 31 uses a Network-NetworkInterface (NNI) protocol for internal network signaling or for signalingbetween private networks. The NNI may be specified by extending the UNIprotocol (ATM Forum 3.1 Signaling Protocol) by specifying additionalmessages fields, states, and transitions. UNI is a protocol by which anexternal network accesses an edge OTS of the optical network.

For example, the NNI may include a path Type-Length-Value field in its“create” message. It may also have to support a crankback feature incase the setup fails. The major requirements for the NNI are listedbelow.

Capability Description Create light path Normal and crankback Modifylight path Change bandwidth parameters Disjoint light path Establishlight path disjoint from specified existing light paths Destroy lightpath Teardown channel Failure Recovery Link or node failure TrafficPre-emption Terminate low priority traffic in case of failure BackupEstablish pre-defined backup links NMS Interface Set MIB variablesExternal Network Backbone Network Interconnection Interface

20.2 Signaling Subnetwork (OSC)

The primary function of the signaling network is to provide connectivityamong the Node Managers of the different OTSs. An IP network may be usedthat is capable of supporting both signaling as well as networkmanagement traffic. For signaling messages, TCP may be used as thetransport protocol. For network management, either TCP or UDP may beused, depending upon the specific application.

FIG. 32 depicts an example of a signaling network having three OTSs, OTSA (3210), OTS B (3220), and OTS C (3230), an NMS 3240 that communicateswith OTS B 3220 (and all other OTSs via OTS B) via an Ethernet 3245, apath requester 3215 and path head 3216 that communicate with the OTS A3210 via an Ethernet 3217, and a path tail 3235 that communicates withthe OTS C 3230 via an Ethernet 3232. The path requester 3215, path head3216 and path tail 3235 denote client equipment that is external to theall-optical network. The internal signaling network may use the OSCwithin the optical network, in which case the facilities are entirelywithin the optical network and dedicated to the signaling and managementof the optical network. The OSC is not directly available to externalclient elements.

Each Node Manager may have its own Ethernet for local communication withthe client equipment. Also, a gateway node may have an additionalEthernet link for communication with the NMS manager if they areco-located. The signaling network has its own routing protocol fortransmission of messages between OTSs as well as within an NMS.Moreover, for fail-safe operation, the signaling network may be providedwith its own NMS that monitors the status and performance of thesignaling network, e.g., to take corrective actions in response to faultconditions, and generate performance data for the signaling network.

21. Protection/Restoration Flow

Referring to the Path Restoration function 3115 and Protection function3145 of FIG. 31, the all-optical network may provide a service recoveryfeature in response to failure conditions. Both line and path protectionmay be provided such that recovery can be performed within a very shortperiod of time comparable to SONET (<50 ms). In cases where recoverytime requirements are less stringent, path restoration under the controlof the NMS may provide a more suitable capability.

Moreover, for SONET clients, client-managed protection may be providedby allowing the client to request disjoint paths, in which case theprotection mechanisms utilized by the client are transparent to theoptical network.

The recovery capability may include 1:1 line protection by having fouroptical fibers between OTSs—a primary and a backup in each direction.When a link or node fails, all paths in the affected link are re-routed(by pre-defined links) as a whole (e.g., on a line basis) rather than byindividual path (e.g., on a path basis). While this is less bandwidthefficient, it is simpler to implement than path protection and isequivalent to SONET layer services. The re-routing is predefined viaNetwork Management in a switch table such that when a failure occurs,the re-routing can be performed in real-time (<50 ms per hop).

Path protection re-routes each individual circuit when a failure occurs.Protection paths may be dedicated and carry a duplicate data stream(1+1), dedicated and carry a pre-emptable low priority data stream(1:1), or shared (1:N).

FIGS. 33( a)–(c) compare line and path protection where two light paths,shown as λ₁ and λ₂, have been setup. FIG. 33( a) shows the normal case,where two signaling paths are available between nodes “1” and “6” (i.e.,path 1-2-4-5-6 and path 1-2-3-5-6). λ₁ traverses nodes 1-2-3-5-6 intravelling toward its final destination, while λ₂ traverses nodes 1-2-3in travelling toward its final destination.

FIG. 33( b) shows the case where line protection is used. In particular,consider the case where link 2-3 fails. With line protection, allchannels affected by the failure are re-routed over nodes 2-4-5-3. Inparticular, λ₁ is routed from node 5-3, and then back from 3-5-6, whichis inefficient since λ₁ travels twice between nodes “3” and “5”, therebyreducing the availability of the 3-5 path for backup traffic.

FIG. 33( c) shows the case where path protection is used. With pathprotection, the light paths λ₁ and λ₂ are each routed separately in anoptimum way, which eliminates the inefficiency of line protection. Inparticular, λ₁ is routed on nodes 1-2-4-5-6, and λ₂ is routed on nodes1-2-4-5-3.

Moreover, the backup fiber (here, the fiber between nodes 2-4-5) neednot be used under normal conditions (FIG. 33( a)). However, pre-emptabletraffic, e.g., lower priority traffic, may be allowed to use the backupfiber until a failure occurs. Once a failure occurs, the pre-emptabletraffic is removed from the backup fiber, which is then used fortransport of higher-priority traffic. The client having thelower-priority traffic is preferably notified of the preemption.

Protection and restoration in large complex mesh networks may also beprovided. Protection features defined by the ODSI, OIF, and IETFstandards bodies can also be included as they become available.

Protection services can also include having redundant hardware at theOTSs, such as for the Node Manager and other line cards. The redundancyof the hardware, which may range from full redundancy to single stringoperation, can be configured to meet the needs of the service provider.Moreover, the hardware can be equipped with a comprehensive performancemonitoring and analysis capability so that, when a failure occurs, aswitch over to the redundant, backup component is quickly made withoutmanual intervention. In case of major node failures, traffic can bere-routed around the failed node using line protection.

22. Network Management System Software

The Network Management System is a comprehensive suite of managementapplications that is compatible with the TMN model, and may support TMNlayers 1 to 3. Interfaces to layer 4, service layer management, may alsobe provided so that customer Operational Support Systems (OSSs) as wellas third party solutions can be deployed in that space.

The overall architecture of the NMS is depicted in FIG. 34. The ElementManagement Layer 3404 corresponds to layer 2 of the TMN model, while theNetwork Management Layer 3402 components correspond to layer 3 of theTMN model. The functions shown are achieved by software running on theNMS and NMS agents at the Node Managers.

A common network management interface 3420 at the Network ManagementLayer provides an interface between: (a) applications 3405 (such as aGUI), customer services 3410, and other NMSs/OSSs 3415, and (b) aconfiguration manager 3425, connection manager 3430, 3440, fault manager3445, and performance manager 3450, which may share commonresources/services 3435, such as a database server, which uses anappropriate database interface, and a topology manager 3440. Thedatabase server or servers may store information for the managers 3425,3430, 3445 and 3450. The interface 3420 may provides a rich set ofclient interfaces that include RMI, EJB and CORBA, which allow thecarrier to integrate the NMS with their systems to perform end-to-endprovisioning and unify event information. Third-party services andbusiness layer applications can also be easily integrated into the NMSvia this interface. The interface 3420 may be compatible with industrystandards where possible.

The GUI 3405 is an integrated set of user interfaces that may be builtusing Java (or other similar object oriented) technology to provide aneasy-to-use customer interface, as well as portability. The customer canselect a manager from a menu of available GUI views, or drill down to anew level by obtaining a more detailed set of views.

The customer services may include, e.g., protection and restoration,prioritized light paths, and other services that are typically sold tocustomers of the network by the network operator.

The “other NMSs” 3415 refer to NMSs that are subservient to a root NMSin a hierarchical optical network structure or an NMS hierarchy. TheOSSs are switching systems other than the OTS system described herein.

The configuration manager 3425 provides a switch level view of the NMS,and may provide functions including provisioning of the Node Managersand LCMs, status and control, and installation and upgrade support. Theconfiguration manager 3425 may also enable the user, e.g., via the GUI3405, to graphically identify the state of the system, boards, and lowerlevel devices, and to provide a point and click configuration to quicklyconfigure ports and place them in service. The configuration manager maycollect switch information such as IP address and switch type, as wellas card-specific information such as serial number and firmware/softwarerevision.

The connection manager 3430 provides a way to view existing light pathconnections between OTSs, including connections within the OTS itself,and to create such connections. The connection manager 3430 supportssimple cross connects as well as end-to-end connections traversing theentire network. The user is able to dictate the exact path of a lightpath by manually specifying the ports and cross connects to use at anOTS. Or, the user may only specify the endpoints and let the connectionmanager set up the connection automatically. Generally, the endpoints ofa connection are OA ports, and the intermediate ports are TP ports. Theuser may also select a wavelength for the connection. The types ofconnections supported include Permanent Optical Circuit (POC), SwitchedOptical Circuit (SOC), as well as Smart Permanent Optical Circuit(SPOC). SOC and SPOC connections are routed by the network elementrouting and signaling planes. SOC connections are available for viewingonly.

The topology manager 3440 provides a NMS topological view of thenetwork, which allows the user to quickly determine, e.g., via the GUI3405, all resources in the network, including links and OTSs in thenetwork, and how they are currently physically connected. The user canuse this map to obtain more detailed views of specific portions of thenetwork, or of an individual OTS, and even access a view of an OTS'sfront panel. For instance, the user can use the topological view toassist in making end-to-end connections, where each OTS or subnet in thepath of a connection can be specified. Moreover, while the topologymanager 3440 provides the initial view, the connection manager 3430 iscalled upon to set up the actual connection.

The fault manager 3445 collect faults/alarms from the OTSs as well asother SNMP-compliant devices, and may include functions such as alarmsurveillance, fault localization, correction, and troubleadministration. Furthermore, the fault manager 3445 can be implementedsuch that the faults are presented to the user in an easy to understandway, e.g., via the GUI 3405, and the user is able to sort the faults byvarious methods such as device origination, time, severity, etc.Moreover, the faults can be aggregated by applying rules that arepredefined by the network administrator, or customer-defined.

The performance manager 3450 performs processing related to theperformance of the elements/OTSs, as well as the network as a whole.Specific functionalities may include performance quality assurance,performance monitoring, performance management control, and performanceanalysis. An emphasis may be on optical connections, including the QoSand reliability of the connection. The performance manager 3450 allowsthe user to monitor the performance of a selected port of channel on anOTS. In particular, the performance manager may display data inreal-time, or from archived data.

These managers 3425, 3430, 3445 and 3450 may provide specificfunctionality and share information, e.g., via Jini, and using anassociated Jini server. Moreover, the manager may store associated datain one or more database servers, which can be configured in a redundantmode for high availability.

Furthermore, a common network management interface 3455 at the ElementManagement Layer provides an interface between: (a) the configurationmanager 3425, connection manager 3430, fault manager 3445 andperformance manager 3450, and (b) an agent adapter function 3460 and an“other adapter” function 3465. The agent adapter 3460 may communicatewith the OTSs in the optical network 3462 using SNMP and IP, in whichcase corresponding SNMP agents and IP agents are provided at the OTSs.The SNMP agent at the OTSs may also interface with other NMSapplications. SNMP is an industry standard interface that allowsintegration with other NMS tools. The interface from the NMS to the OTSin the optical network 3462 may also use a proprietary interface, whichallows greater flexibility and efficiency than SNMP alone. The otheradapter function 3465 refers to other types of optical switches otherthan the OTSs described herein that the NMS may manage.

In summary, the NMS provides a comprehensive capability to manage an OTSor a network of OTSs. A user-friendly interface allows intuitive controlof the element/OTS or network. Finally, a rich set of northboundinterfaces allows interoperability and integration with OSS systems.

Moreover, the NMS may be an open architecture system that is based onstandardized Management Information Bases (MIBs). At this time, ODSI hasdefined a comprehensive MIB for the UNI. However, additional MIBs arerequired, e.g., for NNI signaling and optical network enhancements toOSPF routing. The NMS of the present invention can support the standardMIBs as they become available, while using proprietary MIBs in areaswhere the standards are not available.

The NMS may be implemented in Java (or similar object oriented)technology, which allows the management applications to easilycommunicate and share data, and tends to enable faster softwaredevelopment, a friendlier (i.e., easier to use) user interface,robustness, self-healing, and portability. In particular, Java toolssuch as Jini, Jiro, Enterprise Java Beans (EJB), and Remote MethodInvocation (RMI) may be used.

RMI, introduced in JDK 1.1, is a Java technology that allows theprogrammer to develop distributed Java objects similar to using localJava objects. It does this by keeping separate the definition ofbehavior, and the implementation of the behavior. In other words, thedefinition is coded using a Java interface while the implementation onthe remote server is coded in a class. This provides a networkinfrastructure to access/develop remote objects.

The EJB specification defines an architecture for a transactional,distributed object system based on components. It defines an API thatthat ensures portability across vendors. This allows an organization tobuild its own components or purchase components. These server-sidecomponents are enterprise beans, and are distributed objects that arehosted in EJB containers and provide remote services for clientsdistributed throughout the network.

Jini, which uses RMI technology, is an infrastructure for providingservices in a network, as well as creating spontaneous interactionsbetween programs that use these services. Services can be added orremoved from the network in a robust way. Clients are able to rely uponthe availability of these services. The Client program downloads a Javaobject from the server and uses this object to talk to the server. Thisallows the client to talk to the server even though it does not know thedetails of the server. Jini allows the building of flexible, dynamic androbust systems, while allowing the components to be built independently.A key to Jini is the Lookup Service, which allows a client to locate theservice it needs.

Jiro is a Java implementation of the Federated Management Architecture.A federation, for example, could be a group of services at one location,i.e., a management domain. It provides technologies useful in buildingan interoperable and automated distributed management solution. It isbuilt using Jini technology with enhancements added for a distributedmanagement solution, thereby complementing Jini. Some examples of thebenefits of using Jiro over Jini include security services and directsupport for SNMP.

FIG. 35 illustrates an NMS hierarchy in accordance with the presentinvention. Advantageously, scalability may be achieved via the NMShierarchical architecture, thus allowing a networks from a few OTSs tohundreds of OTSs to still be manageable and using only the processingpower of the necessary number of managing NMSs. In such an architecture,each NMS instance in an NMS hierarchy (which we may also refer to as“manager”), manages a subset of OTSs (with the “root” NMS managing, atleast indirectly through its child NMSs, all the OTSs managed by thehierarchy). For example, NMS 1 (3510) manages NMS 1.1 (3520) and NMS 1.2(3525). NMS 1.1 (3520) manages NMS 1.1.1 (3530), which in turn manages afirst network 3540, and NMS 1.1.2 (3532), which in turn manages a secondnetwork 3542. NMS 1.2 (3525) manages NMS 1.2.1 (3534), which in turnmanages a third network 3544, and NMS 1.2.2 (3536), which in turnmanages a fourth network 3546. Each instance of the NMS in the hierarchymay be implemented as shown in FIG. 34, including having one moredatabase servers for use by the managers of the different functionalareas.

The number of OTSs that an NMS instance can manage depends on factorssuch as the performance and memory of the instance's underlyingprocessor, and the stability of the network configuration. The hierarchyof NMS instances can be determined using various techniques. In theevent of failure of a manager, another manager can quickly recover theNMS functionality. The user can see an aggregated view of the entirenetwork or some part of the network without regard to the number ofmanagers being deployed.

One feature of multiple NMSs controlling multiple networks is therobustness and scalability provided by the hierarchical structure of themanaging NMSs. The NMSs form a hierarchy dynamically, through anelection process, such that a management structure can be quicklyreconstituted in case of failure of some of the NMSs. Furthermore, theNMS provide the capability to configure each OTS and dynamically modifythe connectivity of OTSs in the network. The NMS also enables thenetwork operators to generate on-the-fly statistical metrics forevaluating network performance.

23. Node Manager Software

The control software at the OTS includes the Node Manager software andthe Line Card Manager software. As shown in FIG. 36, the Node Managersoftware 3600 includes Applications layer software 3610 and CoreEmbedded System Services layer 3630 software running on top of anoperating system such as V×Works (Wind River Systems, Inc., Alameda,Calif.). The LCM software has Core Embedded System Services devicedrivers for the target peripheral hardware such as the GbE and OC-nSONET interfaces.

The Applications layer 3610 enables various functions, such as signalingand routing functions, as well as node-to-node communications. Forexample, assume it is desired to restore service within 50 msec for acustomer using a SONET service. The routing and signaling functions areused to quickly communicate from one node to another when an alarm hasbeen reported, such as “the link between Chicago and New York is down.”So, the Applications software 3610 enables the nodes to communicate witheach other for selecting a new route that does not use the faulty link.

Generally, to minimize the amount of processing by the Applicationssoftware 3610, information that is used there is abstracted as much aspossible by the Core Embedded Software 3641 and the System Services3630.

In particular, the Applications layer 3610 may include applications suchas a Protection/Fault Manager 3612, UNI Signaling 3614, NNI Signaling3615, Command Line Interface (CLI) 3616, NMS Database Client 3617,Routing 3618, and NMS agent 3620, each of which is described in furtherdetail below.

The System Services layer software 3630 may include services such asResource Manager 3631, Event Manager 3632, Software Version Manager3633, Configuration Manager 3634, Logger 3635, Watchdog 3636, FlashMemory Interface 3637, and Application “S” Message Manager 3638, each ofwhich is described in further detail below.

The Node Manager's Core Embedded Control Software 3641 is provided belowan “S” interface and the System Services software 3630.

23.1 Node Manager Core Embedded Software

The Node Manager Core Embedded software 3641 is provided between the “S”interface 3640 and the “D” interface 3690. The “D” (drivers) messageinterface 3690 is for messages exchanged between the LCMs and the NodeManager via the OTS's internal LAN, while the “S” (services) messageinterface 3640 is for messages exchanged between the applicationsoftware and the Core Embedded software on the Node Manager.

Generally, these managers ensure that inter-process communication cantake place. In particular, the Node Manager “D” message manager 3646receives “D” messages such as raw Ethernet packets from the LCM andforwards them to the appropriate process. The Node Manager “S” MessageManager 3642 serves a similar general function: providing inter-processcommunication between messages from the System Services layer 3630 andthe Node Manager Core Embedded software. The inter-process communicationprovided by the “S” Interface is typically implemented quite differentlyfrom the “D” Interface since it is not over a LAN but within a singleprocessor. These interfaces, which may use, e.g., header files ortables, are described further in the section entitled “Node ManagerMessage Interfaces.”

Below the “S” interface 3640, the Node Manager's Core Embedded softwarefurther includes a Node Configuration Manager 3644, which is a mastertask for spawning other tasks, shown collectively at 3660, at the NodeManager, and may therefore have a large, complex, body of code. Thismanager is responsible for managing the other Node Manager processes,and knows how to configure the system, such as configuring around ananomaly such as a line card removal or insertion. Moreover, this manager3644 determines how many of the tasks 3662, 3664, 3666, 3668, 3670,3672, 3674, 3676 and 3678 need to be started to achieve a particularconfiguration.

The tasks at the Node Manager Core Embedded software are line cardtasks/processes for handling the different line card types. Theseinclude a TP_(—)IN task 3662, an OA_(—)IN task 3644, an OPM task 3666, aclock task 3668, a TP_(—)EG task 3670, an OA_(—)EG task 3672, an OSFtask 3674, an ALI task 3676 and an OSM task 3678. The “−1” notationdenotes one of multiple tasks that are running for correspondingmultiple line cards of that type when present at the OTS. For example,TP_(—)IN-1 represents a task running for a first TP_(—)IN card.Additional tasks for other TP_(—)IN cards are not shown specifically,but could be denoted as TP_(—)IN-2, TP_(—)IN-3, and so forth.

Managers, shown collectively at 3650, manage resources and systemservices for the line card tasks. These managers include a DatabaseManager 3652, an Alarms Manager 3654, and an Optical Cross Connect (OXC)Manager 3656.

In particular, the Database Manager 3652 may manage a database ofnon-volatile information at the Node Manager, such as data forprovisioning the LCMs. This data may include, e.g., alarm/faultthresholds that are to be used by the LCMs in determining whether todeclare a fault if one of the monitored parameters of the line cardscrosses the threshold. Generally, the Database Manager 3652 manages acollection of information that needs to be saved if the OTS fails/goesdown—similar to a hard disk. As an example of the use of the DatabaseManager 3652, when the OTS is powered up, or when a line card isinserted into a slot in the OTS bay, the associated LCM generates adiscovery packet for the Node Manager to inform it that the line card isup and exists. This enables the line cards to be hot swappable, that is,they can be pulled from and re-inserted into the slots at any time.After receiving the discovery packet, the Node Manager uses the Databasemanager 3652 to contact the database to extract non-volatile data thatis needed to provision that line card, and communicates the data to theLCM via the OTS's LAN. The Node Manager's database may be provided usingthe non-volatile memory resources discussed in connection with FIG. 5.

The Alarms Manager 3654 receives alarm/fault reports from the LCMs(e.g., via any of the tasks 3660) when the LCMs determine that a faultcondition exists on the associated line card. For example, the LCM mayreport a fault to the Alarms Manager 3654 if it determines that amonitored parameter such as laser current consumption has crossed aminimum or maximum threshold level. In turn, the Alarms Manager 3654 mayset an alarm if the fault or other anomaly persists for a given amountof time or based on some other criteria, such as whether some otherfault or alarm condition is present, or the status of one or more othermonitored parameters. Furthermore, the presence of multiple alarms maybe analyzed to determine if they have a common root cause. Generally,the Alarms Manager 3654 abstracts the fault and/or alarm information totry to extract a story line as to what caused the alarm, and passes thisstory up to the higher-level Event Manager 3632 via the “S” interface3640.

Using the push model, the Event Manager 3632 distributes the alarm eventto any of the software components that have registered to receive suchan event. A corrective action can then be implemented locally at theOTS, or at the network-level.

The OXC Manager 3656 makes sense of how to use the different line cardsto make one seamless connection for the customer. For example, using aGUI at the NMS, the customer may request a light path connection fromLos Angeles to San Francisco. The NMS decides which OTSs to route thelight path through, and informs each OTS via the OSC of the next-hop OTSin the light path. The OTS then establishes a light path, e.g., by usingthe OXC Manager 3656 to configure an ALI line card, TP_(—)IN line card,OA_(—)EG line card, a wavelength, and several other parameters that haveto be configured for one cross connect. For example, the OXC Manager3656 may configure the OTS such that port 1 on TP_(—)IN is connected toport 2 on TP_(—)OUT. The OXC Manager 3656 disassembles the elements of across connection and disseminates the relevant information at a lowlevel to the involved line cards via their LCMs.

23.2 System Services

23.2.1 Resource Manager

The Resource Manager 3631 performs functions such as maintaininginformation on resources such as wavelengths and the state of thecross-connects of the OTS, and providing cross-connect setup andteardown capability. In particular, the Resource Manager performs theinteraction with the switch hardware during path creation, modification,and termination. The context diagram of the Resource Manager is shown inFIG. 43. The legend 4330 indicates whether the communications betweenthe components use the Event Manager, an API and TCP, or messagepassing. The Resource Manager is responsible for setting up networkdevices upon receiving requests from the NMS Agent (in case ofprovisioning) or the Signaling component (for a signaled setup). TheResource Manager provides an API that enables other components 4320 toobtain current connection data. Also, the Resource Manager obtainsconfiguration data via an API provided by the Configuration Manager.

For the provisioned requests, which may be persistent, the associatedparameters are stored in flash memory 4310, e.g., via the Flashinterface 3637, which may be DOS file based. Upon reset, the ResourceManager retrieves the parameters from flash memory via the FlashInterface and restores them automatically.

For signaled requests, which may be non-persistent, the associatedparameters may be stored in RAM at the Node Manager. Upon reset, theselightpaths must be re-established based on user requests, or otherswitches could re-establish them.

The Resource Manager component also logs all relevant events via theLogger, updates its MIB, and provides its status to the Watchdogcomponent.

23.2.2 Event Manager

The Event Manager 3632 receives events from the Core Embedded systemsoftware 3641 and distributes those events to high level components(e.g., other software components/functions at the System Services 3630and Applications 3610). It is also used for communication between highlevel components in cases where the communication is one- way (asopposed to request/response). FIG. 44 depicts its context diagram.

The Event Manager sends events to components based on theirregistrations/subscriptions to the events. That is, in an importantaspect of the push model of the present invention, components cansubscribe/unsubscribe to certain events of interest to them. Anyapplication that wants to accept events registers with the Event Manager3632 as an event listener. Moreover, there is anonymous delivery ofevents so that specific destinations for the events do not have to benamed. For example, when something fails in the hardware, an alarm issent to whoever (e.g., which application) has registered for that typeof alarm. Advantageously, the sender of the alarm does not have to knowwho is interested in particular events, and the receivers of the eventsonly receive the types of events in which they are interested. The OTSsoftware architecture thus uses a push model since information is pushedfrom a lower layer to a higher layer in near real-time.

The Event Manager may be used as a middleman between two components formessage transfer. For example, a component A, which wants to send amessage X to another component B, sends it to the Event Manager.Component B must subscribe to the message X in order to receive it fromthe Event Manager.

In particular, the event library software (EventLib) may include thefollowing routines:

EventRegister( )—register for an event to get an event message when theevent occurs;

EventUnRegister( )—un-register for an event; and

EventPost( )—post an event.

These routines return ERROR when they detect an error. In addition, theyset an error status that elaborates the nature of the error.

Normally, high-level applications, e.g. signaling, routing, protection,and NMS agent components, register for events that are posted by CoreEmbedded components, such as device drivers. High-level componentsregister/un-register for events by calling EventRegister()/EventUnRegister( ). Core Embedded components use EventPost( ) to postevents.

The Event Dispatcher may be implemented via POSIX message queues forhandling event registration, un-registration, and delivery. It creates amessage queue, ed_(—)dispQ, when it starts. Two priority levels, highand low, are supported by ed_(—)dispQ. When a component registers for anevent by calling EventRegister( ), a registration event is sent toed_(—)dispQ as a high priority event. Event Dispatcher registers thecomponent for that event when it receives the registration event. If theregistration is successful an acknowledgment event is sent back to theregistering component. A component should consider the registrationfailed if it does not receive an acknowledgment within a short period oftime. It is up to the component to re-register for the event. Acomponent may register for an event for multiple times with the same ordifferent message queues. If the message queue is the same, laterregistration will over-write earlier registration. If the message queuesare different, multiple registrations for the same event will co-exist,and events will be delivered to all message queues when they are posted.

Furthermore, event registration may be permanent or temporary. Permanentregistrations are in effect until cancelled by EventUnRegister( ).EventUnRegister( ) sends a un-register event (a high priority event) toed_(—)dispQ for Event Dispatcher to un-register the component for thatevent. Temporary registrations are cancelled when the lease timeexpired. A component may pre-maturely cancel a temporary registration bycalling EventUnRegister( ). If the un-registration is successful, anacknowledgment event is delivered to the message queue of the component.

When a component uses EventPost( ) to post an event, the posted event isplaced in ed_(—)dispQ, too. An event is either a high priority or a lowpriority event. To prevent low priority events from filling uped_(—)dispQ, the low priority event is not queued when posted ifed_(—)dispQ is more than half full. This way, at least half ofed_(—)dispQ is reserved for high priority events. Event Dispatcherdelivers an event by moving the event from ed_(—)dispQ to the messagequeues of registered components. So, a component must create a POSIXmessage queue before registering for an event and send the message queuename to the Event Dispatcher when it registers for that event. Moreover,a component may create a blocking or non-blocking message queue. If themessage queue is non-blocking, the component may set up a signal handlerto get notification when an event is placed in its message queue.

If the message queue of a component is full when Event Dispatcher triesto deliver an event, the event is silently dropped. Therefore,components should ensure there is space in its message queue to preventan event from being dropped.

23.2.3 Software Version Manager

The Software Version Manager (SVM) 3633 is responsible for installing,reverting, backing up and executing of software in the Node Manager andLCMs. Its context diagram is depicted in FIG. 45. The SVM maintains andupdates software on both the Node Manager and the LCMs by keeping trackof the versions of software that are used, and whether a newer versionis available. Generally, different versions of Node Manager software andLCM software can be downloaded remotely from the NMS to the Node Managerfrom time to time as new software features are developed, software bugsare fixed, and so forth. The Node Manager distributes the LCM softwareto the LCMs. The SVM keeps a record of which version of software iscurrently being used by the Node Manager and LCMs.

In particular, the SVM installs new software by loading the softwareonto flash memory, e.g., at the Node Manager. The SVM performs backingup by copying the current software and saving it on another space on theflash memory. The SVM performs the reverting operation by copying theback up software to the current software. Finally, the SVM performs theexecution operation by rebooting the Node Manager or the LCMs.

In particular, for installation, the SVM receives an install commandfrom the NMS agent that contains the address, path and filename of thecode to be installed. The SVM may perform a File Transfer Protocol (FTP)operation to store the code into its memory. Then, it uses the DOS Flashinterface services 3637 to store the code into the flash memory. Inperforming the backup operation for the Node Manager software, the SVMreceives the backup command from the NMS agent. The SVM uses the DOSFlash interface to copy the current version of the code to a backupversion. In the revert operation for the Node Manager software, the SVMreceives the revert command from the NMS agent and uses the DOS Flashinterface to copy the backup version of the software to the currentversion.

The Node Manager software is executed by rebooting the Node Managercard.

The Installation, reverting, backing up and executing operations canalso be performed on the software residing on the line cards. Inparticular, for installation, the software/firmware is first “FTPed”down to the Node Manager's flash memory. Then, the new firmware isdownloaded to the line card. This new code is stored in the line card'sflash memory. The new code is executed by rebooting the line card.

23.2.4 Configuration Manager

The Configuration Manager 3634 maintains the status of all OTS hardwareand software components. Its context diagram is shown in FIG. 46. Thelegend 4610 indicates whether the communications between the componentsuse the Event Manager, an API and TCP, or message passing. During thefirst OTS system boot up, the Configuration Manager obtains the desiredconfiguration parameters from the database/server (or possibly aconfiguration file) at the NMS. The LCMs are responsible for monitoringthe status of the line cards. When a line card becomes active, itimmediately generates a Discovery message that the LCM for each opticalcard forwards to the Event Manager 3632 that is running on the NodeManager. The Configuration Manager receives these messages bysubscribing to them at the Event Manager. It then compares the storedconfiguration versus the reported configuration. If there is adifference, the Configuration Manager sets the configuration accordingto the stored data by sending a message to the LCM via the Event Managerand S-Interface. It also reports an error and stores the desiredconfiguration in the Node Manager's flash memory.

When the system is subsequently re-booted, the operation is identical,except the desired configuration is stored in flash memory.

The LCMs are configured to periodically report a status of their opticalline cards. Also, when a device fails or has other anomalous behavior,an event message such a fault or alarm is generated. The ConfigurationManager receive these messages via the Event Manager, and issues anevent message to other components. Moreover, while not necessary, theConfiguration Manager may poll the LCMs to determine the line cardstatus if it is desired to determine the status immediately.

If the configuration table in the Node Manager's flash memory iscorrupted, the Configuration Manager may request that thedatabase/server client gets the information (configuration parameters)via the database/server, which resides in the NMS host system. Afterconfiguring the devices, the Configuration Manager posts an event to theEvent Manager so that other components (e.g., NMS Agent and the ResourceManager) can get the desired status of the devices.

The desired configuration can be changed via CLI or NMS command. Afterthe Configuration Manager receives a request from the NMS or CLI tochange a device configuration, the Configuration manager sends an “S”message down to the LCMs to satisfy the request. Upon receiving theacknowledge message that the request was carried out successfully, theConfiguration Manager sends an acknowledgement message to the requester,stores the new configuration into the database service, logs a messageto the Logger, and post an event via the Event Manager.

Moreover, the NMS/CLI can send queries to the Configuration Managerregarding the network devices' configurations. The Configuration Managerretrieves the information from the database and forwards them to theNMS/CLI. The NMS/CLI can also sends a message to the ConfigurationManager to change the reporting frequency or schedule of the device/linecard.

23.2.5 Logger

The Logger 3635 sends log messages to listening components such asdebugging tasks, displays, printers, and files. These devices may bedirectly connected to the Node Manager or connected via a socketinterface.

The Logger's context diagram is shown in FIG. 47. The Logger iscontrolled via the CLI, which may be implemented as either a localservice or remote service via Telnet.

The control may specify device(s) to receive the Logging messages (e.g.,displays, files, printers—local or remote), and the level of loggingdetail to be captured (e.g., event, error event, parameter set).

23.2.6 Watchdog

The Watchdog component 3638 monitors the state (“health”) of other(software) components in the Node Manager by verifying that thecomponents are working.

23.2.7 Flash Memory Interface

A Disk Operating System (DOS) file interface may be used to provide aninterface 3637 to the flash memory on the Node Manager for allpersistent configuration and connection data. Its context diagram isdepicted in FIG. 48. The legend 4820 indicates that the componentscommunicate using an API and TCP. The Resource Manager 3631 andConfiguration Manager 3634 access the Flash Memory 4810 as if it were aDOS File System. Details of buffering and actual writing to flash arevendor-specific.

23.2.8 Application “S” Message Manager

The Application “S” Message Manager receives messages from the NodeManager's Core Embedded software, also referred to as control planesoftware.

23.3 Applications Layer

23.3.1 Protection/Fault Manager

The primary function of the Protection/Fault Manager component is torespond to alarms by isolating fault conditions and initiating servicerestoration. The Protection/Fault Manager isolates failures and restoresservice, e.g., by providing alternate link or path routing to maintain aconnection in the event of node or link failures. As depicted in FIG.37, the Protection/Fault Manager interfaces with the Logger 3635,WatchDog 3636, Resource Manager 3631, Configuration Manager 3634, EventManager 3632, NMS Agent 3620, NNI Signaling 3615 and Other Switches/OTSs3710. The legend 3720 indicates the nature of the communications betweenthe components. The Protection/Fault Manager subscribes to the EventManager to receive events related to the failure of links or networkdevices. When the Protection/Fault Manager receives a failure event andisolates the cause of the alarm, it determines the restorative actionand interacts with the appropriate application software to implement it.If there is problem isolating or restoring service, the problem ishanded over to the NMS for resolution.

Some service providers may elect to perform their own protection byrequesting two disjoint paths. With this capability, the serviceprovider may implement 1+1 or 1:1 protection as desired. When a failureoccurs, the service provider can perform the switchover without anyassistance from the optical network. However, the optical network isresponsible for isolating and repairing the failure.

Using the Event Manager, the Protection/Fault component also logs majorevents via the Logger component, updates its MIB, and provides itsstatus to the Watchdog component. It also updates the Protectionparameters in the shared memory.

23.3.2 UNI Signaling

The Signaling components includes the User-Network Interface (UNI)signaling and the internal Network-Network Interface (NNI) signaling.The primary purpose of signaling is to establish a lightpath between twoendpoints. In addition to path setup, it also performs endpointRegistration and provides a Directory service such that users candetermine the available endpoints.

The UNI signaling context diagram is depicted in FIG. 38. The UNI usesboth message passing and APIs provided by other components tocommunicate with other components. The legend 3830 indicates whether thecommunications between the components use an API and TCP, or messagepassing.

The UNI component provides a TCP/IP interface with User devices 3810,e.g., devices that access the optical network via an OTS. If the UserDevice does not support signaling, a NMS proxy signaling agent 3820resident on an external platform performs this signaling.

When a valid “create lightpath” request is received, the UNI invokes theNNI to establish the path. In addition to creating a lightpath, usersmay query, modify or delete a lightpath.

The UNI Signaling component 3614 obtains current configuration andconnection data from the Configuration and Resource Managers,respectively. It logs major events via the Logger component, updates itsMIB used by the SNMP Agent, and provides a hook to the WatchDogcomponent to enable the WatchDog to keep track of its status.

23.3.3 NNI Signaling

The NNI signaling component 3615, depicted in FIG. 39, performs theinternal signaling between switches in the optical network, e.g., usingMPLS signaling. The legend 3910 indicates whether the communicationsbetween the components use the Event Manager, an API and TCP, or messagepassing.

As discussed, requests for service to establish a lightpath between twoendpoints may be received over the UNI from an external device or aproxy signaling agent. Upon receipt of the request, UNI signalingvalidates the request and forwards it, with source and destinationendpoints, to the NNI signaling function for setup. Source-based routingmay be used, in which case NNI must first request a route from theRouting component 3618. Several options are available, e.g., the usermay request a path disjoint from an existing path.

The Routing component 3618 returns the selected wavelength and set ofswitches/OTSs that define the route. Then, the NNI signaling componentrequests the Resource Manager 3631 to allocate the local hardwarecomponents implementing the path, and forwards a create message to thenext switch in the path using TCP/IP over the OSC.

Each OTS has its local Resource Manager allocate hardware resources tothe light path. When the path is completed, each OTS returns anacknowledgment message along the reverse path confirming the successfulsetup, and that the local hardware will be configured. If the attemptfailed due to unavailability of resources, the resources that had beenallocated along the path are de-allocated. In order for other components(other than UNI, e.g., Routing) to learn if an attempt if the path setupwas successful, the NNI distributes (posts) a result event using theEvent Manager 3632.

Moreover, the NNI Signaling component 3615 obtains current configurationdata from the Configuration Manager 3634, and connection data from theResource Manager 3631. It also logs major events via the Loggercomponent 3635, updates its MIB used by the SNMP Agent, and provides ahook to the WatchDog component 3636 to enable the WatchDog to keep trackof its status.

23.3.4 Command Line Interface

The CLI task 3616, an interface that is separate from the GUI interface,provides a command-line interface for an operator via a keyboard/displayto control or monitor OTSs. The functions of the CLI 3616 includesetting parameters at bootup, entering a set/get for any parameter inthe Applications and System Services software, and configuring theLogger. The TL-1 craft interface definition describes the command andcontrol capabilities that are available at the “S” interface. Table 5lists example command types that may be supported.

TABLE 5 TL-1 Craft Command List Craft Command Parameters DescriptionRtrv-alm Type, slot, Retrieve alarm messages severity Rtrv-crs Type,port Retrieves cross connect information Rtrv-eqpt Address-id Retrievesthe equipage (configuration) of the OTS node Rtrv-hist Start, endRetrieves the event history Rtrv-ali Port, wavelength, Retrieves the ALIport parameters mode Rtrv-node N/A Retrieves OTS node parametersRtrv-pmm Slot, port, Retrieves the performance monitor wavelength meas.Rtrv-port Port Retrieves per port performance measurements Rtrv-prot-swsPort Retrieves path protection connections Set-ali Out-port, in-port,Sets ALI port parameters mode Set-node Id, date, time, Sets OTS nodeparameters alm-delay Set-port Port, wavelength, Sets port and wavelengththresholds thresh

23.3.5 NMS Database Client

Optionally, an NMS database client 3617 may reside at the Node Managerto provide an interface to one or more database servers at the NMS. Onepossibility is to use LDAP servers. Its context diagram is depicted inFIG. 40. As shown, the database/server client 3617 interacts with theNMS's database server, and with the Configuration Manager 3634. Uponrequest from the Configuration manager, the database client contacts theserver for configuration data. Upon receiving a response from theserver, the client forwards the data to the Configuration Manager. Thelegend 4020 indicates whether the communications between the componentsuse the Event Manager, or an API and TCP.

Since the Configuration Data is stored in the Node Manager's flashmemory, the database client may be used relatively infrequently. Forexample, it may be used to resolve problems when the storedconfiguration is not consistent with that obtained via the LCM'sdiscovery process.

Moreover, there may be primary and backup database servers, in whichcase the client keeps the addresses of both servers. If the primaryserver does not function, after waiting for a pre-determined period, theclient forwards the request to the backup server.

Moreover, when the Configuration Manager makes changes to itsconfiguration table, the Configuration Manager posts an event to theEvent Manager. The Event Manager forwards the event to the NMS Agent,which in turn forwards the event to the NMS application. The NMSapplication recognizes the event and contacts the server to update itstable.

23.3.6 Routing

The Routing Component 3618 computes end-to-end paths in response to arequest from the NNI component. The context diagram, FIG. 41, depictsits interfaces with the other components. The legend 4110 indicateswhether the communications between the components use the Event Manager,an API and TCP, or message passing.

The Routing Component, which may implement the OSPF routing algorithmwith optical network extensions, is invoked by the NNI Signalingcomponent at the path source during setup. Routing parameters are inputvia the SNMP Agent.

Routing is closely related to the Protection/Fault Manager. As part ofthe protection features, the Routing component may select paths that aredisjoint (either link disjoint or node and link disjoint as specified bysignaling) from an existing path.

Moreover, as part of its operation, the Routing component exchanges LinkState Advertisement messages with other switches. With the informationreceived in these messages, the Routing component in each switchmaintains a complete view of the network such that it can compute apath.

23.3.7 NMS Agent

The embedded NMS Agent 3620 provides the interface between NMSapplications 4210 (e.g., configuration, connection, topology,fault/alarm, and performance) and the Applications resident on the NodeManager. The NMS agent may use SNMP and a proprietary method. FIG. 42shows the context diagram of the NMS Agent. The legend 4220 indicateswhether the communications between the components use the Event Manager,an API and TCP, or message passing. The NMS Agent operates using a “pullmodel”—all of the SNMP data is stored locally with the relevantcomponent (e.g., UNI, NNI, Routing, Protection). When the NMS Agent mustrespond to a Get request, it pulls the information from its source.

The NMS Agent receives requests from an NMS application and validatesthe request against its MIB tables. If the request is not validated, itsends an error message back to the NMS. Otherwise, it sends the requestusing a message passing service to the appropriate component, such asthe Signaling, Configuration Manager, or Resource Manager components.

For non-Request/Response communications, the NMS agent may subscribe toevents from the Event managers. The events of interest include the“change” events posted by the Resource Manager, Configuration Managerand the UNI and NNI components, as well as messages from the LCMs. Uponreceiving events from the Event Manager or unsolicited messages fromother components (e.g., Signaling), the NMS Agent updates its MIB and,when necessary, sends the messages to the NMS application using a trap.

24. Line Card Manager Software

FIG. 49 illustrates a Line Card Manager software architecture inaccordance with the present invention.

In the OTS control hierarchy, the LCM software 4900 is provided belowthe “D” interface 3690, and generally includes a Core Embedded controllayer to provide the data telemetry and I/O capability on each of thephysical interfaces, and an associated operating system that providesthe protocols (e.g., TCP/IP) and timer features necessary to supportreal-time communications. The LCM software 4900, which may run on top ofan operating system such as V×Works, includes an LCM “D” Message Manager4970 for sending messages to, and receiving messages from, the NodeManager “D” Message Manager 3646 via the “D” interface 3690. Thismanager 4970 is an inter-process communication module which has a queueon it for queuing messages to the Node Manager. An LCM ConfigurationManager 4972 is a master process for spawning and initializing all otherLCM tasks, and performs functions such as waking up the LCM board,configuring the LCM when the system/line card comes up, and receivingvoltages and power.

The LCM line card tasks 4973 include tasks for handling a number of linecards, including an TP_(—)IN handler or task 4976, an OA_(—)IN handler4978, a OPM handler 4980, a clock (CLK) handler 4982, a TP_(—)EG handler4984, an OA_(—)EG handler 4986, an OSF handler 4988, an ALI handler4990, and an OSM handler 4992. Here, the line card handlers can bethought of as being are XORed such that when the identity of the pack(line card) is discovered, only the corresponding pack handler is used.Advantageously, the LCM software 4900 is generic in that it has softwarethat can handle any type of line card, so there is no need to provide aseparate software load for each LCM according to a certain line cardtype. This simplifies the implementation and maintenance of the OTS.Alternatively, it is possible to provide each LCM with only the softwarefor a specific type of line card.

Each of the active line card handlers can declare faults based onmonitored parameters that they receive from the respective line card.Such faults may occur, e.g., when a monitored parameter is out of apre-set, normal range. The line card handlers may signal to the customerthat fault conditions are present and should be examined in furtherdetail, by using the Node Manager and NMS.

Moreover, the line card handlers use push technology in that they pushevent information up to the next layer, e.g., the Node Manager, asappropriate. This may occur, for example, when a fault requiresattention by the Node Manager or the NMS. For example, a fault may bepushed up to the Alarms Manager 3654 at the Node Manager Core EmbeddedSoftware, where an alarm is set and pushed up to the Event manager 3632for distribution to the software components that have registered toreceive that type of alarm. Thus, a lower layer initiates thecommunication to the higher layer.

The clock handler 4982 handles a synchronizing clock signal that ispropagated via the electrical backplane (LAN) from the Node Manager toeach LCM. This is necessary, for example, for the line cards that handleSONET signals and thereby need a very accurate clock for multiplexingand demultiplexing.

Generally speaking, the LCM performs telemetry by constantly collectingdata from the associated line card and storing it in non-volatilememory, e.g., using tables. However, only specific information is sentto the Node Manager, such as information related to a threshold crossingby a monitored parameter of the line card, or a request, e.g., by theNMS through the Node Manager, to read something from the line card. Atransparent control architecture is provided since the Node Manager canobtain fresh readings from the LCM memory at any time.

The Node Manager may keep a history log of the data it receives from theLCM.

25. Node Manager Message Interfaces

As mentioned, the Node Manager supports two message interfaces, namelythe “D” Message Interface, which is for messages exchanged between theLCMs and the Node Manager, and the “S” Message interface, which is formessages exchanged between the application software and the CoreEmbedded system services software on the Node Manager.

25.1 “D” Message Interface Operation

The “D” message interface allows the Node Manager to provision andcontrol the line cards, retrieve status on demand and receive alarms asthe conditions occur. Moreover, advantageously, upgraded LCMs can beconnected in the future to the line cards using the same interface. Thisprovides great flexibility in allowing baseline LCMs to be fielded whileenhanced LCMs are developed. Moreover, the interface allows the LCMs andNode Manager to use different operating systems.

The Core Embedded Node Manager software builds an in-memory image of allprovisioned data and all current transmission-specific monitoredparameters. The Node Manager periodically polls each line card for itsmonitored data and copies this data to the in-memory image in SDRAM. Thein-memory image is modified for each alarm indication and clearing of analarm, and is periodically saved to flash memory to allow rapidrestoration of the OTS in the event of a system reboot, selected linecard reboot or selected line card swap. The in-core memory image isorganized by type of line card, instance of line card and instances ofinterfaces or ports on the type of line card. Each LCM has a localin-memory image of provisioning information and monitored parametersspecific to that board type and instance.

The “D” message interface uses a data link layer protocol (Layer 2) thatis carried by the OTS's internal LAN. The line cards and Node Managermay connect to this LAN to communicate “D” message using RJ-45connectors, which are standard serial data interfaces. A “D” Messageinterface dispatcher may run as a V×Works task on the LCM. The LCM isable to support this dispatcher as an independent process since the LCMprocessor is powerful enough to run a multi-tasking operating system.The data link layer protocol, which may use raw Ethernet frames(including a destination field, source field, type field and checkbits), avoids the overhead of higher-level protocol processing that isnot warranted inside the OTS. All messages are acknowledged, and messageoriginators are responsible for re-transmitting a message if anacknowledgement is not received in a specified time. A sniffer connectedto the OTS system's internal LAN captures and display all messages onthe LAN. A sniffer is a program and/or device that monitors datatraveling over a network. The messages should be very easy tocomprehend.

Preferably, all messages are contained in one standard Ethernet framepayload to avoid message fragmenting on transmission, and reassemblyupon receipt. Moreover, this protocol is easy to debug, and aids insystem debugging. Moreover, this scheme avoids the problem of assigninga network address to each line card. Instead, each line card isaddressed using its built-in Ethernet address. Moreover, the NodeManager discovers all line cards as they boot, and adds each line card'saddress to an address table.

This use of discovery messages combined with periodic audit messagesobviates the need for equipage leads (i.e., electrical leads/contactsthat allow monitoring of circuits or other equipment) in the electricalbackplane, and the need for monitoring of such leads by the NodeManager. In particular, when it reboots, an LCM informs the Node Managerof its presence by sending it a Discovery message. Audit messages areinitiated by the Node Manager to determine what line cards are presentat the OTS.

25.1.1 “D” Interface Message Types

The following message types are defined for the “D” interface.

-   READ Message Pair—Used by the Node Manager to retrieve monitored    parameters from the LCMs. The Node Manager sends Read Request    messages to the LCMs, and they respond via Read Acknowledge    messages.-   WRITE Message Pair—Used by the Node Manager to write provisioning    data to the LCMs. The Node Manager sends Write Request messages to    the LCMs, and they respond via Write Acknowledge messages.-   ALARM Message Pair—Used by the LCM to inform the Node Manager of    alarm conditions. A LCM sends an Alarm message to the Node Manager    indicating the nature of the alarm, and the Node Manager responds    with an Alarm Acknowledge message.-   DISCOVERY message (autonomous)—Used by the LCM to inform the Node    Manager of its presence in the OTS when the line card reboots. The    Node Manager responds with a Discovery Acknowledge message.-   AUDIT message—Used by the Node Manager to determine what line cards    are present in the OTS. The LCM responds with a Discovery    Acknowledge message.

25.1.2 “D” Interface Message Definitions

Tables 6–11 define example “D” message interface packets. Note that someof the messages, such as the “discovery” and “attention” messages, areexamples of anonymous push technology since they are communications thatare initiated by a lower layer in the control hierarchy to a higherlayer.

TABLE 6 Instruction Codes in LCM to Node Manager Packets Code (hex) NameDescription 60 Discovery first packet sent after power-up 61 attentionsending alarm and data 11 data sending data requested 31 ack acknowledgedata write packet 36 nack error - packet not accepted

TABLE 7 LCM originated “Discovery” Packet Size Function (16-bit words)Description Dest. address 3 hex FF:FF:FF:FF:FF:FF (Node Manager) Sourceaddress 3 hex <OTS LCM MAC PREFIX>: (LCM) pack pos. ID protocol key 1hex BEEF sw process tag 2 initially 0, after time-out 1 instruction 1hex 0060 pack type 1 pack type, version, serial number data size 1 hex0000

TABLE 8 LCM originated “Attention” Packet Size Function (16-bit words)Description Dest. address 3 Node Manager MAC address from (Node Manager)received packet Source address 3 hex <OTS LCM MAC PREFIX>: (LCM) packposition ID Protocol key 1 hex BEEF Sw process tag 2 initially 0, aftertime-out 1 Instruction 1 hex 0061 Pack type 1 pack type, version, serialnumber Data size 1 number of 16-bit data words to follow ADC measures 16last measured values of analog inputs Limit select 1 16 limit selectbits in use Alarm mask 1 16 alarm mask bits in use Status reg. 4 64 packstatus bits Status reg. 4 64 status alarm level select bits level selectStatus reg. 4 64 status alarm mask bits in use mask ADC 2 16 analoglimit exception bits attn bits Status 4 64 status exception bits attnbits Device results 32 control and results registers

TABLE 9 LCM “Response” Packet Size Function (16-bit words) DescriptionDest. address 3 Node Manager address from received (Node Manager) packetSource address 3 hex <OTS LCM MAC PREFIX>: (LCM) pack position IDProtocol key 1 hex BEEF Sw process tag 2 copied from request packetInstruction 1 see Table 8 Address 1 copied from request packet Data size1 number of 16-bit data words to follow Data n payload

TABLE 10 Instruction Codes in Node Manager to LCM Packets Code (Hex)Name Description 50 First ack acknowledging the “Discovery” packet 51Alarm ack acknowledging “Attention” packet 01 Read read data fromaddress indicated 02 Write write data to address indicated 03 Wsw writeswitch 15 Bitwrite bit position to change: where mask word bit = 1 datato write: data word 41 Reload causes re-loading the MPC8255microcontroller from EPROMs 42 Soft reset causes “soft reset” of thepack 43 Hard reset causes “hard reset” of the pack

TABLE 11 Node Manager - originated packets Size Function (16-bit words)Description Dest. address 3 hex <OTS LCM MAC PREFIX>: pack (Node pos. IDManager) Source address 3 MAC address of OTS Node Manager (LCM) Protocolkey 1 hex BEEF sw process tag 2 sequence number Instruction 1 see Table8 Address 1 LCM register, or other valid on-pack location data size 1number of 16-bit data words to follow Data n payload

25.2 “S” Message Interface

The “S” message interface of the Node Manager provides the applicationlayer software with access to the information collected and aggregatedat the “D” message interface. Information is available on the CoreEmbedded software side (control plane) of the “S” message interface byline card type and instance for both read and write access. An exampleof read access is “Get all monitored parameters for a particular linecard instance.” An example of write access is “Set all controlparameters for a specific line card instance.” Performance can beincreased by not supporting Gets and Sets on individual parameters.

For example, these messages may register/deregister an application taskfor one or more alarms from all instances of a line card type, providealarm notification, get all monitored parameters for a specific linecard, or set all control parameters for a specific line card.

The “S” message interface is an abstraction layer: it abstracts away,from the application software's perspective, the details by which thelower-level Node Manager software collected and aggregated information.While providing an abstract interface, the “S” Message Interface stillprovides the application layer software with access to the aggregatedinformation and control obtained from the hardware via the “D” MessageInterface, and from the Node Manager state machines. Moreover, the “S”interface defines how the TL-1 craft interface is encoded/decoded by theNode Manager. The TL-1 craft interface definition describes the commandand control capabilities that are available at the “S” interface. Seesection 23.3.4, entitled “Command Line Interface.”

The application software using the “S” Message interface may run as,e.g., one or more V×Works tasks. The Core Embedded software may run as aseparate V×Works task also. To preserve the security afforded by theRTOS to independent tasks, the “S” Message Interface may be implementedusing message queues, which insulates both sides of the interface from ahung or rebooting task on the opposite side of the interface. As for theLCM, this division of the Node Manager software into independent tasksis possible because the Node Manager is powerful enough to run amulti-tasking operating system. Therefore, the present inventive controlarchitecture utilizes the presence of a multi-tasking operating systemat all three of its levels: LCM, Node Manager and NMS. Thismulti-tasking ability has been exploited at all levels of control toproduce a system that is more modularized, and therefore more reliable,than prior approaches to optical network control.

26. Example OTS Embodiment

Summary information of an example embodiment of the OTS is as follows:

Optical Specs: Wavelength capacity: 64 wavelength channels Fiberwavelength density: 8 wavelengths Data rate: Totally transparentPhysical topology: Point-to-Point Lightpath topology: Point-to-PointWavelength spacing: 200 GHz (ITU-grid) Optical bandwidth (channels): Cand L bands Wavelength protection: Selectable on a per lightpath basisOptical Modules: (i) Optical transport Modules (ii) Optical switchingmodule (iii) Optical add/drop module (iv) Optical performance monitoringmodule Access Line Interface Modules: Optical line interface cards: GbE,OC-n/STM-n (i) 16-ports (8 input & 8 output) OC-12 line card (ii)16-ports (8 input & 8 output) OC-48 line card (iii) 16-ports (8 input &8 output) Gigabit Ethernet line card (iv) 4-ports (2 input and 2 output)OC-192 line card Optical Signaling Module: 4-Ports using EthernetSignaling Support IP, Ethernet Packets Node Manager: Processors:MPC8260, MPC755 SDRAM: 256 MB upgradable to 512 MB Flash Memory: 64Mbytes Ethernet Port: 100 BaseT with Auto-Sensing Ethernet Hubs: OEMassembly 10 ports, 1 per shelf Serial Port: 1 EIA 232-D Console PortSoftware Upgrades: Via remote download Line Card Manager: Processor:MPC8260 SDRAM: 64 MB upgradable to 128 MB Flash Memory: 16 MbytesEthernet Port: 100 BaseT with Auto-Sensing Serial Port: 1 EIA 232-DConsole Port Software Upgrades: Via local download Backplanes: Opticalbackplane Electrical backplane Ethernet LAN interconnecting Node Managerand LCMs

27. Glossary A/D Analog-to-Digital ABR Available Bit Rate ADM Add-DropMultiplexer ALI Access Line Interface API Application ProgrammingInterface ATM Asynchronous Transfer Mode CBR Constant Bit Rate CIT CraftInterface Terminal CORBA Common Object Request Broker Architecture DACDigital-to-Analog Converter DMA Direct Memory Access DWDM DenseWavelength Division Multiplexing EDFA Erbium Doped Fiber Amplifier EJBEnterprise Java Beans EEPROM Electrically Erasable PROM EPROM ErasableProgrammable Read-Only Memory FCC Fast Communication Channel Gbps Gigabits per second GbE Gigabit Ethernet GPIO General Purpose Input-Output(interface) GUI Graphical User Interface HDLC High-Level Data LinkControl IETF Internet Engineering Task Force I²C Inter IntegratedCircuit (bus) IP Internet Protocol ITU International TelecommunicationsUnion JDK Java Development Kit (Sun Microsystems, Inc.) L2 Level 2(cache) or Layer 2 (of OSI model) LCM Line Card Manager LDAP LightweightDirectory Access Protocol (IETF RFC 1777) LSR Label Switch Router MACMedium Access Control (layer) MB Megabyte MEMS Micro-Electro-MechanicalSystem MIB Management Information Base MPC Motorola ® PowerPC(microprocessor) MPLS Multi Protocol Label Switching NEBS NetworkEquipment Building Standards NMS Network Management System nm NanometersOA Optical Access Or Optical Amplifier OA_(—)Eg Optical Access EgressOA_(—)In Optical Access Ingress OADM Optical Add Drop Multiplexer OC-nOptical Carrier - specifies the speed (data rate) of a fiber opticnetwork that conforms to the SONET standard. “n” denotes the speed as amultiple of 51.84 Mbps, such that OC-12 = 622.08 Mbps, OC-48 = 2.488Gbps, etc. ODSI Optical Domain Service/System Interconnect OEO OpticalTo Electrical To Optical (conversion) OEM Original EquipmentManufacturer OPM Optical Performance Monitoring Module OSC OpticalSignaling Channel OSF Optical Switch OSI Open Standards InterconnectionOSM Optical Signaling Module OSNR Optical Signal To Noise Ratio OSPFOpen Shortest Path First OSS Operational Support Systems OTS All-OpticalTransport Switching System OXC Optical Cross Connect PCI PeripheralComponent Interconnect PCMCIA Personal Computer Memory CardInternational Association PHY Physical (layer) PIN Photo Intrinsic POPPoint Of Presence PVC Permanent Virtual Circuit QoS Quality of ServiceRISC Reduced Instruction Set Computer RMI Remote Method Invocation RWARouting and Wavelength Assignment RTOS Real-Time Operating System RxReceiver SDH Synchronous Digital Hierarchy (Networks) SDRAM SynchronousDynamic Random Access Memory SerDes Serializer/Deserializer SMC SharedMemory Cluster SNMP Simple Network Management Protocol SONET SynchronousOptical Network SPI Special Peripheral Interface STM SynchronousTransport Mode SW Software or Switch TCP Transmission Control ProtocolTDM Time Division Multiplexing TMN Telecommunication Management Network(an ITU-T standard) TP Trunk Port/Transport TP_(—)Eg Transport EgressTP_(—)In Transport Ingress Tx Transmitter UBR Unspecified Bit Rate VBRVariable Bit Rate VME VersaModule Eurocard (bus) WAN Wide Area NetworkWDD Wavelength Division Demultiplexer WDM Wavelength DivisionMultiplexer WXC Wavelength Cross Connect

Accordingly, it can be seen that the present invention provides anall-optical switch that can be selectively configured to providecross-connection and add/drop multiplexing functions in an opticalnetwork. Optical circuit cards are provided in a chassis, and connectedby an optical backplane. A local area network enables control andmonitoring of the cards by a local node manager. The all-optical switchcan be used in an optical network that allows external access networksto access the optical network, including access networks that useGigabit Ethernet and SONET OC-n optical signaling. Wavelength conversionis provided for wavelengths that are not compliant with the all-opticalnetwork. The invention also provides a Node Manager control mechanismthat is local to each switch for configuring and monitoring the switch,as well as distributed Line Card Manager control mechanisms formonitoring and controlling each circuit card. A common, centralizedNetwork Management System control mechanism is also provided forconfiguring and monitoring the switches in the network.

While the invention has been described and illustrated in connectionwith preferred embodiments, many variations and modifications as will beevident to those skilled in this art may be made without departing fromthe spirit and scope of the invention, and the invention is thus not tobe limited to the precise details of methodology or construction setforth above as such variations and modification are intended to beincluded within the scope of the invention.

1. An optical transport switching system for use in an optical network,comprising: an optical access ingress subsystem which is adapted toreceive an optical signal associated with an access network; an opticalaccess egress subsystem; a transport ingress subsystem; a transportegress subsystem; and an optical switch subsystem which is adapted toingress the optical signal into the optical network by opticallycoupling the optical access ingress subsystem to the transport egresssubsystem and which is adapted to selectively provide optical couplingbetween the transport ingress subsystem and at least one of (1) theoptical access egress subsystem, and (2) the transport egress subsystem.2. The system of claim 1, wherein: the optical switch subsystemcomprises an all-optical switch.
 3. The system of claim 1, wherein: theoptical switch subsystem comprises a micro-electro-mechanical switch. 4.The system of claim 1, wherein: the optical switch subsystem isconfigurable to provide add multiplexing by optically coupling aspecified optical output of the optical access ingress subsystem with aspecified optical input of the transport egress subsystem.
 5. The systemof claim 1, wherein: the optical switch subsystem is configurable toprovide drop multiplexing by optically coupling a specified opticaloutput of the transport ingress subsystem with a specified optical inputof the optical access egress subsystem.
 6. The system of claim 1,wherein: the transport ingress subsystem and transport egress subsystemseach communicate via respective optical links with at least onerespective remote node in the optical network.
 7. The system of claim 1,wherein: the optical switch subsystem is adapted to optically couple aspecified optical output of the transport ingress subsystem with atleast one of: (a) a specified optical input of the optical access egresssubsystem, and (b) a specified optical input of the transport egresssubsystem.
 8. The system of claim 1, wherein: the optical switchsubsystem is configurable to provide a wavelength cross-connect byoptically coupling a specified optical output of the transport ingresssubsystem with a specified optical input of the transport egresssubsystem.
 9. The system of claim 8, wherein; the optical switchsubsystem, when configured to provide the wavelength cross-connect, isadapted to route optical signals in the optical network according to adesired routing protocol.
 10. The system of claim 1, wherein: theoptical switch subsystem is adapted to optically couple a specifiedoptical output of the optical access ingress subsystem with at least oneof: (a) a specified optical input of the optical access egresssubsystem, and (b) a specified optical input of the transport egresssubsystem.
 11. The system of claim 1, wherein: the transport ingresssubsystem receives an optical signal multiplex via at least one opticallink of the optical network, and comprises a demultiplexer fordemultiplexing the optical signal multiplex to provide a plurality ofindividual optical signals to be optically coupled by the optical switchsubsystem.
 12. The system of claim 1, wherein: a plurality of individualoptical signals are optically coupled to the transport egress subsystemby the optical switch subsystem, and the transport egress subsystemcomprises a multiplexer for multiplexing the individual optical signalsto provide an optical signal multiplex for transport via at least oneoptical link of the optical network.
 13. The system of claim 1, furthercomprising: an access line interface subsystem for converting an opticalsignal of an access network that has a wavelength that is non-compliantwith the optical network to an optical signal having a wavelength thatis compliant with the optical network.
 14. The system of claim 13,wherein: the access line interface subsystem provides the optical signalhaving the compliant wavelength to the optical access ingress subsystem.15. The system of claim 1, further comprising: an access line interfacesubsystem for converting an optical signal of the optical network thathas a wavelength that is compliant with the optical network to anoptical signal having a wavelength that is non-compliant with theoptical network, but compliant with an access network associated withthe optical network.
 16. The system of claim 15, wherein: the accessline interface subsystem receives the optical signal having thecompliant wavelength from the optical access egress subsystem.
 17. Thesystem of claim 1, further comprising: a node manager for selectivelyconfiguring the optical switch subsystem to provide at least one of anadd/drop multiplexer and a wavelength cross-connect by controlling theoptical coupling provided by the optical switch subsystem.
 18. Thesystem of claim 1, wherein: the transport ingress subsystem andtransport egress subsystem provide optical inputs and outputs,respectively, of a node in the optical network.
 19. The system of claim1, wherein: the optical access ingress subsystem, optical access egresssubsystem, transport ingress subsystem, and transport egress subsystemeach comprise at least one respective optical circuit card.
 20. Thesystem of claim 19, wherein: the cards are receivable in a common bay.21. The system of claim 1, wherein: the subsystems each compriserespective electrical connections for communicating with a common nodemanager via a local area network.
 22. The system of claim 1, wherein:the subsystems each comprise respective optical connections forcommunicating with an optical backplane.
 23. The system of claim 1,further comprising: an optical performance monitoring subsystem foroptically tapping into at least one of the optical access ingresssubsystem, the optical access egress subsystem, the transport ingresssubsystem, and the transport egress subsystem to obtain performance datatherefrom.
 24. The system of claim 1, further comprising: an opticalsignaling subsystem for at least one of: (a) receiving signaling datathrough the transport ingress subsystem, and (b) transmitting signalingdata through the transport egress subsystem.
 25. An optical transportswitching system for use in an optical network, comprising: an opticalaccess ingress subsystem; an optical access egress subsystem which isadapted to direct the optical signal toward an access network; atransport ingress subsystem; a transport egress subsystem; and theoptical switch subsystem is adapted to egress an optical signal from theoptical network by optically coupling the optical signal from thetransport ingress subsystem to the optical access egress subsystem andis adapted to selectively provide optical coupling between the transportegress subsystem and at least one of (1) the optical access ingresssubsystem and (2) the transport ingress subsystem.
 26. An opticaltransport switching system for use in an optical network, comprising:means for switching optical signals; means for providing optical accessingress to the optical network; means for providing optical accessegress from the optical network; means for providing transport ingressto the optical switching means; and means for providing transport egressfrom the optical switching means; wherein: the switching means isadapted to ingress the optical signal into the optical network byoptically coupling the means for providing optical access ingress to themeans for providing transport egress and is adapted to selectivelyprovide optical coupling between the means for providing transportingress and one of (1) the means for providing optical access egress,and (2) the means for providing transport egress.
 27. An opticaltransport switching system for use in an optical network, comprising: areceiving apparatus having a plurality of respective receiving locationsadapted to receive respective optical circuit cards with respectivecontrollers, and a receiving location for receiving a centralcontroller; an optical backplane associated with the receiving apparatusfor optically coupling to the optical circuit cards; and a local areanetwork for electrically coupling the central controller to the circuitcard controllers to enable the central controller to control and monitorthe optical circuit cards.
 28. The system of claim 27, wherein: theoptical circuit cards include at least a transport ingress card, atransport egress card, and a switching fabric card for opticallycoupling the transport ingress card and the transport egress card. 29.The system of claim 27, wherein: the optical backplane comprises opticalfibers.
 30. The system of claim 27, wherein: the optical circuit cardsare of a plurality of card types; and at least some of the receivinglocations are designated for receiving particular ones of the cardtypes.